Process for Making Cyclohexanone

ABSTRACT

Disclosed are processes and systems for making cyclohexanone from a mixture comprising phenol, cyclohexanone, and cyclohexylbenzene, comprising a step of or a device for subjecting at least a portion of the mixture to hydrogenation and a step of or a device for distilling a phenol/cyclohexanone/cyclohexylbenzene mixture to obtain an effluent rich in cyclohexanone.

PRIORITY CLAIM TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/057,947 filed Sep. 30, 2014, and European Application No.15151425.4 filed Jan. 16, 2015, the disclosures of which are fullyincorporated herein by their reference.

FIELD

The present invention relates to processes for making cyclohexanone. Inparticular, the present invention relates to processes for makingcyclohexanone by phenol hydrogenation. The present invention is useful,e.g., in making cyclohexanone from cyclohexylbenzene oxidation andcyclohexylbenzene hydroperoxide cleavage.

BACKGROUND

Cyclohexanone is an important material in the chemical industry and iswidely used in, for example, production of phenolic resins, bisphenol A.ε-caprolactam, adipic acid, and plasticizers. One method for makingcyclohexanone is by hydrogenating phenol.

Currently, a common route for the production of phenol is the Hockprocess. This is a three-step process in which the first step involvesalkylation of benzene with propylene to produce cumene, followed byoxidation of cumene to the corresponding hydroperoxide, and thencleavage of the hydroperoxide to produce equimolar amounts of phenol andacetone. The separated phenol product can then be converted tocyclohexanone by a step of hydrogenation.

It is known from, e.g., U.S. Pat. No. 6,037,513, that cyclohexylbenzenecan be produced by contacting benzene with hydrogen in the presence of abifunctional catalyst comprising a molecular sieve of the MCM-22 typeand at least one hydrogenation metal selected from palladium, ruthenium,nickel, cobalt, and mixtures thereof. This reference also discloses thatthe resultant cyclohexylbenzene can be oxidized to the correspondinghydroperoxide, which can then be cleaved to produce a cleavage mixtureof phenol and cyclohexanone, which, in turn, can be separated to obtainpure, substantially equimolar phenol and cyclohexanone products. Thiscyclohexylbenzene-based process for co-producing phenol andcyclohexanone can be highly efficient in making these two importantindustrial materials. Given the higher commercial value of cyclohexanonethan phenol, it is highly desirable that in this process morecyclohexanone than phenol be produced. While this can be achieved bysubsequently hydrogenating the pure phenol product produced in thisprocess to covert a part or all of the phenol to cyclohexanone, a moreeconomical process and system would be highly desirable.

One solution to making more cyclohexanone than phenol from the abovecyclohexylbenzene-based process is to hydrogenate a mixture containingphenol and cyclohexanone obtained from the cleavage mixture to convertat least a portion of the phenol contained therein to cyclohexanone.However, because the phenol/cyclohexanone mixture invariably contains anon-negligible amount of cyclohexylbenzene, which can be converted intobicyclohexane in the hydrogenation step, and because hydrogenation ofthe phenol/cyclohexane/cyclohexylbenzene mixture can also lead to theformation of cyclohexanol, both resulting in yield loss, this process isnot without challenge.

As such, there is a need for an improved process system for makingcyclohexanone from a mixture containing phenol, cyclohexanone andcyclohexylbenzene.

The present invention satisfies this and other needs.

SUMMARY

The process of the present invention relates to a process for makingcyclohexanone from a first mixture comprising cyclohexanone, phenol, andcyclohexylbenzene. The first mixture is first fed to a primaryfractionation column which produces an upper stream rich incyclohexanone, a middle stream comprising a mixture of cyclohexanone,phenol, cyclohexylbenzene, and some bicyclohexane (largely produced bythe hydrogenation reaction downstream and recycled to the primaryfractionation column), and a lower stream rich in cyclohexylbenzene. Themiddle stream is then fed into a hydrogenation reactor together with ahydrogen stream, where phenol reacts with hydrogen to produce additionalamount of cyclohexanone, and possibly some cyclohexylbenzene reacts withhydrogen to produce bicyclohexane, and possibly some cyclohexanonereacts with hydrogen to produce cyclohexanol. The hydrogenation reactionproduct comprising cyclohexanone, phenol, cyclohexanol,cyclohexylbenzene, and bicyclohexane is then recycled back to theprimary distillation column.

It has been found that by feeding the hydrogenation product mixturecomprising phenol, cyclohexanone, cyclohexylbenzene, and bicyclohexaneproduced from the hydrogenation reactor into the primary fractionationcolumn supplying phenol to the hydrogenation reactor at multiplelocations on the primary fractionation column, one can effectivelymanage bicyclohexane in the primary fractionation column, prevent theformation of a separate bicyclohexane phase therein, and reduce theproduction of bicyclohexane in the hydrogenation reactor.

In a first aspect, the present disclosure relates to a process formaking cyclohexanone, the process comprising: (I) feeding a firstmixture comprising cyclohexanone, phenol, and cyclohexylbenzene into afirst distillation column; (II) obtaining from the first distillationcolumn: (i) a first upper effluent comprising cyclohexanone at aconcentration higher than in the first mixture, phenol, andcyclohexylbenzene; (ii) a first middle effluent comprisingcyclohexanone, phenol at a concentration higher than in the firstmixture, cyclohexylbenzene, and bicyclohexane that may be producedpartially as a result of the hydrogenation reaction downstream; and(iii) a first lower effluent comprising cyclohexylbenzene at aconcentration higher than in the first mixture; (III) feeding at least aportion of the first middle effluent and hydrogen into a hydrogenationreaction zone where phenol reacts with hydrogen and cyclohexylbenzenereacts with hydrogen in the presence of a hydrogenation catalyst underhydrogenation reaction conditions to obtain a hydrogenation reactionproduct comprising cyclohexanone at a concentration higher than in thefirst middle effluent, phenol at a concentration lower than the firstmiddle effluent, cyclohexylbenzene, and bicyclohexane; (IV) obtainingfrom the hydrogenation reaction product multiple streams including afirst liquid product stream and a second liquid product stream; (V)feeding the first liquid product stream into the first distillationcolumn at a location not lower than the location where the first middleeffluent is drawn; and (VI) feeding the second liquid product streaminto the first distillation column at a location lower than the locationwhere the first middle effluent is drawn.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a process/system for makingcyclohexanone from a mixture comprising phenol, cyclohexanone andcyclohexylbenzene including a primary fractionation column T1, ahydrogenation reactor R1, and a cyclohexanone purification column T2.

FIG. 2 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to the process/systemshown in FIG. 1, but comprising modified fluid communications betweenand/or within the primary fractionation column T1 and the hydrogenationreactor R1.

FIG. 3 is a schematic diagram showing a portion of a process/systemsimilar to those shown in FIGS. 1 and 2, but comprising modified fluidcommunications and/or heat transfer arrangement between and/or withinthe primary fractionation column T1 and the cyclohexanone purificationcolumn T2.

FIG. 4 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1 to 3, but comprising a tubular heat exchanger-type hydrogenationreactor R1, where the hydrogenation reaction occurs primarily in vaporphase.

FIG. 5 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1 to 4, but comprising three hydrogenation reactors R3, R5, and R7connected in series, where the hydrogenation reaction occurs primarilyin liquid phase.

FIG. 6 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1 to 5, but comprising modified fluid communications between and/orwithin the primary fractionation column T1 and the hydrogenation reactorR1.

FIG. 7 is a schematic diagram showing a portion of a process/systemsimilar to those shown in FIGS. 1 to 6, but comprising a side strippercolumn T4 before the primary fractionation column T1 configured forremoving at least a portion of the light components from thephenol/cyclohexanone/cyclohexylbenzene feed fed to the primaryfractionation column T1 to reduce or prevent catalyst poisoning in thehydrogenation reactor.

FIG. 8 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1 to 7, but comprising a side stripper column T5 after the primaryfractionation column T1 configured for removing at least a portion ofthe light components from the phenol/cyclohexanone/cyclohexylbenzenefeed fed to the hydrogenation reactor to reduce or prevent catalystpoisoning in the hydrogenation reactor.

FIG. 9 is a schematic diagram showing a portion of a process/systemsimilar to those shown in FIGS. 1 to 8, but comprising a side strippercolumn T6 after the cyclohexanone purification column T2, configured toreduce amounts of light components from the final cyclohexanone product.

DETAILED DESCRIPTION

Various specific embodiments, versions and examples of the inventionwill now be described, including preferred embodiments and definitionsthat are adopted herein for purposes of understanding the claimedinvention. While the following detailed description gives specificpreferred embodiments, those skilled in the art will appreciate thatthese embodiments are exemplary only, and that the invention may bepracticed in other ways. For purposes of determining infringement, thescope of the invention will refer to any one or more of the appendedclaims, including their equivalents, and elements or limitations thatare equivalent to those that are recited. Any reference to the“invention” may refer to one or more, but not necessarily all, of theinventions defined by the claims.

In the present disclosure, a process is described as comprising at leastone “step.” It should be understood that each step is an action oroperation that may be carried out once or multiple times in the process,in a continuous or discontinuous fashion. Unless specified to thecontrary or the context clearly indicates otherwise, each step in aprocess may be conducted sequentially in the order as they are listed,with or without overlapping with one or more other step, or in any otherorder, as the case may be. In addition, one or more or even all stepsmay be conducted simultaneously with regard to the same or differentbatch of material. For example, in a continuous process, while a firststep in a process is being conducted with respect to a raw material justfed into the beginning of the process, a second step may be carried outsimultaneously with respect to an intermediate material resulting fromtreating the raw materials fed into the process at an earlier time inthe first step. Preferably, the steps are conducted in the orderdescribed.

Unless otherwise indicated, all numbers indicating quantities in thepresent disclosure are to be understood as being modified by the term“about” in all instances. It should also be understood that the precisenumerical values used in the specification and claims constitutespecific embodiments. Efforts have been made to ensure the accuracy ofthe data in the examples. However, it should be understood that anymeasured data inherently contain a certain level of error due to thelimitation of the technique and equipment used for making themeasurement.

As used herein, the indefinite article “a” or “an” shall mean “at leastone” unless specified to the contrary or the context clearly indicatesotherwise. Thus, embodiments using “a fractionation column” includeembodiments where one, two or more fractionation columns are used,unless specified to the contrary or the context clearly indicates thatonly one fractionation column is used. Likewise, “a C12+ component”should be interpreted to include one, two or more C12+ components unlessspecified or indicated by the context to mean only one specific C12+component.

As used herein, “wt %” means percentage by weight, “vol %” meanspercentage by volume, “mol %” means percentage by mole, “ppm” meansparts per million, and “ppm wt” and “wppm” are used interchangeably tomean parts per million on a weight basis. All “ppm” as used herein areppm by weight unless specified otherwise. All concentrations herein areexpressed on the basis of the total amount of the composition inquestion. Thus, the concentrations of the various components of thefirst feedstock are expressed based on the total weight of the firstfeedstock. All ranges expressed herein should include both end points astwo specific embodiments unless specified or indicated to the contrary.

In the present disclosure, a location “in the vicinity of” a locationsuch as an end (top or bottom) of a column means a location within adistance of a*Hc from the location such as the end (top or bottom) ofthe column, where He is the height of the column from the bottom to thetop, and a1≦a≦a2, where a1 and a2 can be, independently: 0, 0.01, 0.02,0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14,0.15, 0.16, 0.17, 0.18, 0.19, 0.20, as long as a1<a2. For example, alocation in the vicinity of an end of a column can have an absolutedistance from the end (top or bottom) of at most D meters, where D canbe 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, 0.8, 0.5, 0.4, 0.3, 0.2,0.1, or 0.

An “upper effluent” as used herein may be at the very top or the side ofa vessel such as a fractionation column or a reactor, with or without anadditional effluent above it. Preferably, an upper effluent is drawn ata location in the vicinity of the top of the column. Preferably, anupper effluent is drawn at a location above at least one feed. A “lowereffluent” as used herein is at a location lower than the upper effluent,which may be at the very bottom or the side of a vessel, and if at theside, with or without additional effluent below it. Preferably, a lowereffluent is drawn at a location in the vicinity of the bottom of thecolumn. Preferably, a lower effluent is drawn at a location below atleast one feed. As used herein, a “middle effluent” is an effluentbetween an upper effluent and a lower effluent. The “same level” on adistillation column means a continuous segment of the column with atotal height no more than 5% of the total height of the column.

As used herein, the conversion of a reactant Re1 and the selectivity ofa given product Pro1 in a given reaction system is calculated asfollows. Assuming that a total of n₀ moles of Re1 is charged into thereaction system, the net effect of the process results in n₁ moles ofRe1 converted to Pro1, and the reaction mixture exiting the reactionsystem comprises n₂ moles of residual Re1, then the overall conversionof Re1(Con(Re1)) and the selectivity toward Pro1 (Sel(Pro1)) is obtainedas follows:

Con(Re1)=n ₀ −n ₂ /n ₀×100%, and

Sel(Re1)=n ₁ /n ₀ −n ₂×100%.

Nomenclature of elements and groups thereof used herein are pursuant tothe Periodic Table used by the International Union of Pure and AppliedChemistry after 1988. An example of the Periodic Table is shown in theinner page of the front cover of Advanced Inorganic Chemistry, 6^(th)Edition, by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

As used herein, the term “methylcyclopentanone” includes both isomers2-methylcyclopentanone (CAS Registry No. 1120-72-5) and3-methylcyclopentanone (CAS Registry No. 1757-42-2), at any proportionbetween them, unless it is clearly specified to mean only one of thesetwo isomers or the context clearly indicates that is the case. It shouldbe noted that under the conditions of the various steps of the presentprocesses, the two isomers may undergo isomerization reactions to resultin a ratio between them different from that in the raw materialsimmediately before being charged into a vessel such as a fractionationcolumn.

As used herein, the generic term “dicyclohexylbenzene” (“DiCHB”)includes, in the aggregate, 1,2-dicyclohexylbenzene,1,3-dicylohexylbenzene, and 1,4-dicyclohexylbenzene, unless clearlyspecified to mean only one or two thereof. The term cyclohexylbenzene,when used in the singular form, means mono substitutedcyclohexylbenzene. As used herein, the term “C12” means compounds having12 carbon atoms, and “C12+ components” means compounds having at least12 carbon atoms. Examples of C12+ components include, among others,cyclohexylbenzene, biphenyl, bicyclohexane, methylcyclopentylbenzene,1,2-biphenylbenzene, 1,3-biphenylbenzene, 1,4-biphenylbenzene,1,2,3-triphenylbenzene, 1,2,4-triphenylbenzene, 1,3,5-triphenylbenzene,and corresponding oxygenates such as alcohols, ketones, acids, andesters derived from these compounds. As used herein, the term “C18”means compounds having 18 carbon atoms, and the term “C18+ components”means compounds having at least 18 carbon atoms. Examples of C18+components include, among others, diicyclohexylbenzenes (“DiCHB,”described above), tricyclohexylbenzenes (“TriCHB,” including all isomersthereof, including 1,2,3-tricyclohexylbenzene,1,2,4-tricyclohexylbenzene, 1,3,5-tricyclohexylbenzene, and mixtures oftwo or more thereof at any proportion). As used herein, the term “C24”means compounds having 24 carbon atoms.

The term “MCM-22 type material” (or “material of the MCM-22 type” or“molecular sieve of the MCM-22 type” or “MCM-22 type zeolite”), as usedherein, includes one or more of:

-   -   molecular sieves made from a common first degree crystalline        building block unit cell, which unit cell has the MWW framework        topology. A unit cell is a spatial arrangement of atoms which if        tiled in three-dimensional space describes the crystal        structure. Such crystal structures are discussed in the “Atlas        of Zeolite Framework Types,” Fifth Edition, 2001, the entire        content of which is incorporated as reference;    -   molecular sieves made from a common second degree building        block, being a 2-dimensional tiling of such MWW framework        topology unit cells, forming a monolayer of one unit cell        thickness, desirably one c-unit cell thickness;    -   molecular sieves made from common second degree building blocks,        being layers of one or more than one unit cell thickness,        wherein the layer of more than one unit cell thickness is made        from stacking, packing, or binding at least two monolayers of        one unit cell thickness. The stacking of such second degree        building blocks can be in a regular fashion, an irregular        fashion, a random fashion, or any combination thereof; and    -   molecular sieves made by any regular or random 2-dimensional or        3-dimensional combination of unit cells having the MWW framework        topology.

Molecular sieves of the MCM-22 type include those molecular sieveshaving an X-ray diffraction pattern including d-spacing maxima at12.4±0.25, 6.9±0.15, 3.57±0.07, and 3.42±0.07 Angstrom. The X-raydiffraction data used to characterize the material are obtained bystandard techniques such as using the K-alpha doublet of copper asincident radiation and a diffractometer equipped with a scintillationcounter and associated computer as the collection system.

Materials of the MCM-22 type include MCM-22 (described in U.S. Pat. No.4,954,325), PSH-3 (described in U.S. Pat. No. 4,439,409), SSZ-25(described in U.S. Pat. No. 4,826,667), ERB-1 (described in EuropeanPatent No. 0293032). ITQ-1 (described in U.S. Pat. No. 6,077,498), ITQ-2(described in International Patent Publication No. WO97/17290). MCM-36(described in U.S. Pat. No. 5,250,277), MCM-49 (described in U.S. Pat.No. 5,236,575). MCM-56 (described in U.S. Pat. No. 5,362,697), andmixtures thereof. Other molecular sieves, such as UZM-8 (described inU.S. Pat. No. 6,756,030), may be used alone or together with the MCM-22type molecular sieves as well for the purpose of the present disclosure.Desirably, the molecular sieve used in the catalyst of the presentdisclosure is selected from (a) MCM-49; (b) MCM-56; and (c) isotypes ofMCM-49 and MCM-56, such as ITQ-2.

The process and systems for making cyclohexanone disclosed herein can beadvantageously used for making cyclohexanone from any feed mixturecomprising phenol, cyclohexanone and cyclohexylbenzene. While the feedmay be derived from any process or source, it is preferably obtainedfrom the acid cleavage of a mixture comprising cyclohexylbenzenehydroperoxide and cyclohexylbenzene, which, in turn, is preferablyobtained from aerobic oxidation of cyclohexylbenzene, which, in turn, ispreferably obtained benzene. Steps of these preferred processes aredescribed in detail below.

Supply of Cyclohexylbenzene

The cyclohexylbenzene supplied to the oxidation step can be producedand/or recycled as part of an integrated process for producing phenoland cyclohexanone from benzene. In such an integrated process, benzeneis initially converted to cyclohexylbenzene by any conventionaltechnique, including oxidative coupling of benzene to make biphenylfollowed by hydrogenation of the biphenyl. However, in practice, thecyclohexylbenzene is desirably produced by contacting benzene withhydrogen under hydroalkylation conditions in the presence of ahydroalkylation catalyst whereby benzene undergoes the followingReaction-1 to produce cyclohexylbenzene (CHB):

Alternatively, cyclohexylbenzene can be produced by direct alkylation ofbenzene with cyclohexene in the presence of a solid-acid catalyst suchas molecular sieves in the MCM-22 family according to the followingReaction-2:

U.S. Pat. Nos. 6,730,625 and 7,579,511, International Patent ApplicationNos. WO 2009/131769, and WO 2009/128984 disclose processes for producingcyclohexylbenzene by reacting benzene with hydrogen in the presence of ahydroalkylation catalyst, the contents of which are incorporated hereinby reference in their entirety.

The catalyst employed in the hydroalkylation reaction is a bifunctionalcatalyst comprising a molecular sieve, such as one of the MCM-22 typedescribed above and a hydrogenation metal.

Any known hydrogenation metal may be employed in the hydroalkylationcatalyst, specific, non-limiting, suitable examples of which include Pd,Pt, Rh, Ru, Ir, Ni, Zn, Sn, Co, with Pd being particularly advantageous.Desirably, the amount of hydrogenation metal present in the catalyst isfrom 0.05 wt % to 10.0 wt %, such as from 0.10 wt % and 5.0 wt %, of thetotal weight of the catalyst.

In addition to the molecular sieve and the hydrogenation metal, thehydroalkylation catalyst may comprise one or more optional inorganicoxide support materials and/or binders. Suitable inorganic oxide supportmaterial(s) include, but are not limited to, clay, non-metal oxides,and/or metal oxides. Specific, non-limiting examples of such supportmaterials include: SiO₂, Al₂O₃, ZrO₂, Y₂O₃, Gd₂O₃, SnO, SnO₂, andmixtures, combinations and complexes thereof.

The effluent from the hydroalkylation reaction (hydroalkylation reactionproduct mixture) or from the alkylation reaction (alkylation reactionproduct mixture) may contain some polyalkylated benzenes, such asdicyclohexylbenzenes (DiCHB), tricyclohexylbenzenes (TriCHB),methylcyclopentylbenzene, unreacted benzene, cyclohexane, bicyclohexane,biphenyl, and other contaminants. Thus, typically, after the reaction,the hydroalkylation reaction product mixture is separated bydistillation to obtain a C6 fraction containing benzene, cyclohexane, aC12 fraction containing cyclohexylbenzene and methylcyclopentylbenzene,and a heavies fraction containing, e.g., C18s such as DiCHBs and C24ssuch as TriCHBs. The unreacted benzene may be recovered by distillationand recycled to the hydroalkylation or alkylation reactor. Thecyclohexane may be sent to a dehydrogenation reactor, with or withoutsome of the residual benzene, and with or without co-fed hydrogen, whereit is converted to benzene and hydrogen, which can be recycled to thehydroalkylation/alkylation step.

Depending on the quantity of the heavies fraction, it may be desirableto either (a) transalkylate the C18s such as DiCHB and C24s such asTriCHB with additional benzene or (b) dealkylate the C18s and C24s tomaximize the production of the desired monoalkylated species.

Transalkylation with additional benzene is desirably effected in atransalkylation reactor, which is separate from the hydroalkylationreactor, over a suitable transalkylation catalyst, such as a molecularsieve of the MCM-22 type, zeolite beta, MCM-68 (see U.S. Pat. No.6,049,018), zeolite Y, zeolite USY, and mordenite. The transalkylationreaction is desirably conducted under at least partially liquid phaseconditions, which suitably include a temperature in the range from 100°C. to 300° C. a pressure in the range from 800 kPa to 3500 kPa, a weighthourly space velocity from 1 hr⁻¹ to 10 hr⁻¹ on total feed, and abenzene/dicyclohexylbenzene weight ratio in a range from 1:1 to 5:1.

Dealkylation is also desirably effected in a reactor separate from thehydroalkylation reactor, such as a reactive distillation unit, at atemperature of about 150° C. to about 500° C. and a pressure in a rangefrom 15 to 500 psig (200 to 3550 kPa) over an acid catalyst such as analuminosilicate, an aluminophosphate, a silicoaluminophosphate,amorphous silica-alumina, an acidic clay, a mixed metal oxide, such asWO_(x)/ZrO₂, phosphoric acid, sulfated zirconia and mixtures thereof.Desirably, the acid catalyst includes at least one aluminosilicate,aluminophosphate or silicoaluminophosphate of the FAU, AEL, AFI and MWWfamily. Unlike transalkylation, dealkylation can be conducted in theabsence of added benzene, although it may be desirable to add benzene tothe dealkylation reaction to reduce coke formation. In this case, theweight ratio of benzene to poly-alkylated aromatic compounds in the feedto the dealkylation reaction can be from 0 to about 0.9, such as fromabout 0.01 to about 0.5. Similarly, although the dealkylation reactioncan be conducted in the absence of added hydrogen, hydrogen is desirablyintroduced into the dealkylation reactor to assist in coke reduction.Suitable hydrogen addition rates are such that the molar ratio ofhydrogen to poly-alkylated aromatic compound in the total feed to thedealkylation reactor can be from about 0.01 to about 10.

The transalkylation or dealkylation product mixture comprising benzene,C12s and heavies can then be separated to obtain a C6 fraction, whichcomprises primarily benzene and can be recycled to thehydroalkylation/alkylation step, a C12s fraction comprising primarilycyclohexylbenzene, and a heavies fraction which can be subjected to atransalkylation/dealkylation reaction again or discarded.

The cyclohexylbenzene freshly produced and/or recycled may be purifiedbefore being fed to the oxidation step to remove at least a portion of,among others, methylcyclopentylbenzene, olefins, phenol, acid, and thelike. Such purification may include, e.g., distillation, hydrogenation,caustic wash, and the like.

The cyclohexylbenzene feed to the oxidizing step may contain, based onthe total weight of the feed, one or more of the following: (i)bicyclohexane at a concentration in a range from at 1 ppm to 1 wt %,such as from 10 ppm to 8000 ppm; (ii) biphenyl at a concentration in arange from 1 ppm to 1 wt %, such as from 10 ppm to 8000 ppm; (iii) waterat a concentration up to 5000 ppm, such as from 100 ppm to 1000 ppm; and(iv) olefins or alkene benzenes, such as phenylcyclohexene, at aconcentration no greater than 1000 ppm.

Oxidation of Cyclohexylbenzene

In the oxidation step, at least a portion of the cyclohexylbenzenecontained in the oxidation feed is converted tocyclohexyl-1-phenyl-1-hydroperoxide, the desired hydroperoxide,according to the following Reaction-3:

In exemplary processes, the oxidizing step may be accomplished bycontacting an oxygen-containing gas, such as air and various derivativesof air, with the feed comprising cyclohexylbenzene. For example, astream of pure O2, O2 diluted by inert gas such as N2, pure air, orother O2-containing mixtures can be pumped through thecyclohexylbenzene-containing feed in an oxidation reactor.

The oxidation may be conducted in the absence or presence of a catalyst.Examples of suitable oxidation catalysts include those having astructure of formula (FC-1), (FC-II), or (FC-III) below:

where:

A represents a ring optionally comprising a nitrogen, sulfur, or oxygenin the ring structure, and optionally substituted by an alkyl, analkenyl, a halogen, or a N-, S-, or O-containing group or other group;

X represents a hydrogen, an oxygen free radical, a hydroxyl group, or ahalogen:

R¹, the same or different at each occurrence, independently represents ahalogen, a N-, S-, or O-containing group, or a linear or branchedacyclic alkyl or cyclic alkyl group having 1 to 20 carbon atoms,optionally substituted by an alkyl, an alkenyl, a halogen, or a N-, S-,or O-containing group or other group; and m is 0, 1 or 2.

Examples of particularly suitable catalysts for the oxidation stepinclude those represented by the following formula (FC-IV):

where:

R², the same or different at each occurrence, independently represents ahalogen, a N-, S-, or O-containing group, or an optionally substitutedlinear or branched acyclic alkyl or cyclic alkyl group having 1 to 20carbon atoms; and n is 0, 1, 2, 3, or 4.

One especially suitable catalyst having the above formula (FC-IV) forthe oxidation step is NHPI (N-hydroxyphthalimide). For example, the feedto the oxidizing step can comprise from 10 to 2500 ppm of NHPI by weightof the cyclohexylbenzene in the feed.

Other non-limiting examples of the oxidation catalyst include:4-amino-N-hydroxyphthalimide, 3-amino-N-hydroxyphthalimide,tetrabromo-N-hydroxyphthalimide, tetrachloro-N-hydroxyphthalimide,N-hydroxyhetimide, N-hydroxyhimimide, N-hydroxytrimellitimide,N-hydroxybenzene-1,2,4-tricarboximide, N,N′-dihydroxy(pyromelliticdiimide), N,N′-dihydroxy(benzophenone-3,3′,4,4′-tetracarboxylicdiimide), N-hydroxymaleimide, pyridine-2,3-dicarboximide,N-hydroxysuccinimide, N-hydroxy(tartaric imide),N-hydroxy-5-norbornene-2,3-dicarboximide,exo-N-hydroxy-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide.N-hydroxy-cis-cyclohexane-1,2-dicarboximide,N-hydroxy-cis-4-cyclohexene-1,2 dicarboximide. N-hydroxynaphthalimidesodium salt, N-hydroxy-o-benzenedisulphonimide, andN,N′,N″-trihydroxyisocyanuric acid.

These oxidation catalysts can be used either alone or in conjunctionwith a free radical initiator, and further can be used as liquid-phase,homogeneous catalysts or can be supported on a solid carrier to providea heterogeneous catalyst. Desirably, the N-hydroxy substituted cyclicimide or the N,N′,N″-trihydroxyisocyanuric acid is employed in an amountfrom 0.0001 wt % to 15 wt %, such as from 0.001 wt % to 5 wt %, of thecyclohexylbenzene feed.

Non-limiting examples of suitable reaction conditions of the oxidizingstep include a temperature in a range from 70° C. to 200° C., such as90° C. to 130° C., and a pressure in a range from 50 kPa to 10.000 kPa.A basic buffering agent may be added to react with acidic by-productsthat may form during the oxidation. In addition, an aqueous phase may beintroduced into the oxidation reactor. The reaction may take place in abatch or continuous flow fashion.

The reactor used for the oxidizing step may be any type of reactor thatallows for the oxidation of cyclohexylbenzene by an oxidizing agent,such as molecular oxygen. A particularly advantageous example of thesuitable oxidation reactor is a bubble column reactor capable ofcontaining a volume of the reaction media and bubbling an O₂-containinggas stream (such as air) through the media. For example, the oxidationreactor may comprise a simple, largely open vessel with a distributorinlet for the oxygen-containing gas stream. The oxidation reactor mayhave means to withdraw a portion of the reaction media and pump itthrough a suitable cooling device and return the cooled portion to thereactor, thereby managing the heat generated in the reaction.Alternatively, cooling coils providing indirect cooling, e.g., bycooling water, may be operated within the oxidation reactor to remove atleast a portion of the generated heat. Alternatively, the oxidationreactor may comprise a plurality of reactors in series and/or inparallel, each operating at the same or different conditions selected toenhance the oxidation reaction in the reaction media with differentcompositions. The oxidation reactor may be operated in a batch,semi-batch, or continuous flow manner well known to those skilled in theart.

Composition of the Oxidation Reaction Product Mixture

Desirably, the oxidation reaction product mixture exiting the oxidationreactor contains cyclohexyl-1-phenyl-1-hydroperoxide at a concentrationin a range from Chp1 wt % to Chp2 wt %, based on the total weight of theoxidation reaction product mixture, where Chp1 and Chp2 can be,independently: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70,75, 80, as long as Chp1<Chp2. Preferably, the concentration ofcyclohexyl-1-phenyl-1-hydroperoxide in the oxidation reaction productmixture is at least 20% by weight of the oxidation reaction productmixture. The oxidation reaction product mixture may further compriseresidual cyclohexylbenzene at a concentration in a range from Cchb1 wt %to Cchb2 wt %, based on the total weight of the oxidation reactionproduct mixture, where Cchb1 and Cchb2 can be, independently: 20, 25,30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, as long asCchb1<Cchb2. Preferably, the concentration of cyclohexylbenzene in theoxidation reaction product mixture is at most 65% by weight of theoxidation reaction product mixture.

In addition, the oxidation reaction product mixture may contain one ormore hydroperoxides other than cyclohexyl-1-phenyl-1-hydroperoxidegenerated as byproduct(s) of the oxidation reaction ofcyclohexylbenzene, or as the oxidation reaction product of oxidizablecomponent(s) other than cyclohexylbenzene that may have been containedin the feed supplied to the oxidizing step, such ascyclohexyl-2-phenyl-1-hydroperoxide,cyclohexyl-3-phenyl-1-hydroperoxide, and methylcyclopentylbenzenehydroperoxides. These undesired hydroperoxides are present at a totalconcentration from Cu1 wt % to Cu2 wt %, where Cu1 and Cu2 can be,independently: 0.1, 0.2, 0.3, 0.5, 0.7, 0.9, 1.0, 1.2, 1.4, 1.5, 1.6,1.8, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, as long asCu1<Cu2. They are undesirable because they may not convert into phenoland cyclohexanone in the cleavage reaction at the desired conversionand/or selectivity, resulting in overall yield loss.

As noted above, the oxidation reaction product mixture may also containphenol as a further by-product of the oxidation reaction. Theconcentration of phenol (CPh) in the oxidation reaction product mixtureexiting the oxidation reactor(s) can range from CPh1 ppm to CPh2 ppm,where CPh1 and CPh2 can be, independently: 50, 60, 70, 80, 90, 100, 150,200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850,900, 950, 1000, 1500, 2000, as long as CPh1<CPh2.

The oxidation reaction product mixture may contain water. Theconcentration of water in the oxidation reaction product mixture exitingthe oxidation reactor may range from C1a ppm to C1b ppm, based on thetotal weight of the oxidation reaction product mixture, where C1a andC1b can be, independently: 30, 40, 50, 60, 70, 80, 90, 100, 150, 200,250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900,950, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, or 5000, as long asC1a<C1b.

The oxidation reaction product mixture may also contain part or all ofany catalyst, such as NHPI, supplied to the oxidizing step. For example,the oxidation reaction product mixture may contain from 10 to 2500 ppmof NHPI, such as from 100 to 1500 ppm by weight of NHPI.

Treatment of the Oxidation Reaction Product Mixture

In the process of the present disclosure, before being supplied to thecleavage step, at least a portion of the oxidation reaction productmixture may be separated. The separation process may include subjectingat least a portion of the oxidation reaction product mixture to vacuumevaporation so as to recover: (i) a first fraction comprising themajority of the cyclohexyl-1-phenyl-1-hydroperoxide and other higherboiling components of the oxidation reaction product mixture portion,such as other hydroperoxides and NHPI catalyst, if present in theoxidation reaction product mixture portion; and (ii) a second fractioncomprising a major portion of the cyclohexylbenzene, phenol, if any, andother lower boiling components of the oxidation reaction product mixtureportion.

Desirably, in the first fraction, the concentration ofcyclohexyl-1-phenyl-1-hydroperoxide can range from Cc1 wt % to Cc2 wt,and the concentration of cyclohexylbenzene can range from Cd1 wt % toCd2 wt %, based on the total weight of the first fraction, where Cc1 andCc2 can be, independently: 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90,as long as Cc1<Cc2; and Cd1 and Cd2 can be, independently: 10, 15, 20,25, 30, 35, 40, 45, 50, as long as Cd1<Cd2.

Advantageously, in the second fraction, the concentration ofcyclohexyl-1-phenyl-1-hydroperoxide can range from Cc3 wt % to Cc4 wt %,and the concentration of cyclohexylbenzene can range from Cd3 wt % toCd4 wt %, based on the total weight of the second fraction, where Cc3and Cc4 can be, independently: 0.01, 0.05, 0.10, 0.20, 0.40, 0.50, 0.60,0.80, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, as long asCc3<Cc4; and Cd3 and Cd4 can be, independently: 90, 92, 94, 95, 96, 97,98, or even 99, as long as Cd3<Cd4.

Because cyclohexylbenzene hydroperoxide is prone to decomposition atelevated temperatures, e.g., at above 150° C., the vacuum evaporationstep to separate the oxidation reaction product mixture into the firstand second fractions is conducted at a relatively low temperature, e.g.,no higher than 130° C., or no higher than 120° C. or even no higher than110° C. Cyclohexylbenzene has a high boiling point (239° C. at 101 kPa).Thus, at acceptable cyclohexylbenzene-removal temperatures,cyclohexylbenzene tends to have very low vapor pressure. Accordingly,preferably, to effectively remove a meaningful amount ofcyclohexylbenzene from the oxidation reaction product mixture, theoxidation reaction product mixture is subjected to a very low absolutepressure, e.g., in a range from Pc1 kPa to Pc2 kPa, where Pc1 and Pc2can be, independently: 0.05, 0.10, 0.15, 0.20, 0.25, 0.26, 0.30, 0.35,0.40, 0.45, 0.50, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00,1.50, 2.00, 2.50, 3.00, as long as Pc1<Pc2. Particularly advantageously.Pc1=0.25, and Pc2=1.5.

After separation of the oxidation reaction product mixture into thefirst and second fractions, part or all of the first fraction can berouted directly to the cleavage step. All or a portion of the firstfraction may be cooled before passage to the cleavage step so as tocause crystallization of the unreacted imide oxidation catalyst. Theimide crystals may then be recovered for reuse either by filtration orby scraping from a heat exchanger surface used to effect thecrystallization.

The second fraction produced from the oxidation reaction product mixturemay be treated to reduce the level of phenol therein before part or allof the cyclohexylbenzene in the second fraction is recycled to thehydrogenation.

Treatment of the second fraction can comprise contacting at least aportion of the second fraction with an aqueous composition comprising abase under conditions such that the base reacts with the phenol toproduce a phenoate species which remains in the aqueous composition. Astrong base, that is a base having a pKb value less than 3, such as lessthan 2, 1, 0, or −1, is desirably employed in the treatment of thesecond fraction. Particularly suitable bases include hydroxides ofalkali metals (e.g., LiOH, NaOH, KOH, RbOH), hydroxides of alkalineearth metals (Mg(OH)₂, Ca(OH)₂, Sr(OH)₂, Ba(OH)₂), and mixtures of oneor more thereof. Phenol can react with these hydroxides to formphenoates, which typically have higher solubility in water than phenolper se. A particularly desirable base is NaOH, which is cost efficientand capable of reacting with phenol in the second fraction to producesodium phenoate. It should be noted that, when a hydroxide is used asthe base, because of the reaction of CO₂ present in the atmosphere withthe hydroxide, the aqueous composition may comprise, at variousconcentrations, one or more of a corresponding carbonate, bicarbonate,or carbonate-hydroxide complex. Desirably, the aqueous compositioncomprising the base has a pH of at least 8, preferably at least 10.

Contacting of the second fraction with the aqueous compositioncomprising a base produces an aqueous phase containing at least part ofthe phenol and/or a derivative thereof from the second fraction and anorganic phase containing cyclohexylbenzene and having a reducedconcentration of phenol as compared with the second fraction. Desirably,the phenol concentration in the organic phase is in the range from CPh7ppm to CPh8 ppm, based on the total weight of the organic phase, whereCPh7 and CPh8 can be, independently: 0, 10, 20, 30, 40, 50, 100, 150,200, 250, as long as CPh7<CPh8.

The organic phase can then be separated from the aqueous phase, forexample, spontaneously under gravity, and can then be recycled to theoxidizing step as a third fraction either directly, or more preferably,after water washing to remove base contained in the organic phase.

Cleavage Reaction

In the cleavage reaction, at least a portion of thecyclohexyl-1-phenyl-1-hydroperoxide decomposes in the presence of anacid catalyst in high selectivity to cyclohexanone and phenol accordingto the following desired Reaction-4:

The cleavage product mixture may comprise the acid catalyst, phenol,cyclohexanone, cyclohexylbenzene, and contaminants.

The acid catalyst can be at least partially soluble in the cleavagereaction mixture, is stable at a temperature of at least 185° C. and hasa lower volatility (higher normal boiling point) than cyclohexylbenzene.

Acid catalysts preferably include, but are not limited to, Bronstedacids, Lewis acids, sulfonic acids, perchloric acid, phosphoric acid,hydrochloric acid, p-toluene sulfonic acid, aluminum chloride, oleum,sulfur trioxide, ferric chloride, boron trifluoride, sulfur dioxide, andsulfur trioxide. Sulfuric acid is a preferred acid catalyst.

The cleavage reaction preferably occurs under cleavage conditionsincluding a temperature in a range from 20° C. to 200° C., or from 40°C. to 120° C., and a pressure in a range from 1 to 370 psig (at least 7kPa, gauge and no greater than 2,550 kPa, gauge), or from 14.5 psig to145 psig (from 100 kPa, gauge to 1,000 kPa, gauge) such that thecleavage reaction mixture is completely or predominantly in the liquidphase during the cleavage reaction.

The cleavage reaction mixture can contain the acid catalyst at aconcentration in a range from Cad ppm to Cac2 ppm by weight of the totalweight of the cleavage reaction mixture, where Cac1 and Cac2 can be,independently: 10, 20, 30, 40, 50, 60, 80, 100, 150, 200, 250, 300, 350,400, 450, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500,4000, 4500, or even 5000, as long as Cac1<Cac2. Preferably, Cac1 is 50,and Cac2 is 200.

Conversion of hydroperoxides, such ascyclohexyl-1-phenyl-1-hydroperoxide, and conveniently allcyclohexyl-1-phenyl-1-hydroperoxide and other hydroperoxides, may bevery high in the cleavage reaction, e.g., at least AA wt %, where AA canbe 90.0, 91.0, 92.0, 93.0, 94.0, 95.0, 96.0, 97.0, 98.0, 99.0, 99.5,99.9, or even 100, the percentage based on the weight of a givenhydroperoxide, or of all hydroperoxides fed to the cleavage step. Thisis desirable because any hydroperoxide, even thecyclohexyl-1-phenyl-1-hydroperoxide, becomes a contaminant in thedownstream processes.

Desirably, each mole of cyclohexyl-1-phenyl-1-hydroperoxide produces onemole of phenol and one mole of cyclohexanone. However, due to sidereactions, the selectivity of the cleavage reaction to phenol can rangefrom Sph1% to Sph2% and the selectivity to cyclohexanone can range fromSch1% to Sch2%, where Sph1, Sph2, Sch1, and Sch2 can be, independently:85, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or even 99.5, aslong as Sph1<Sph2, and Sch1<Sch2.

Besides the cleavage feed comprising cyclohexylbenzene hydroperoxide,cyclohexylbenzene and other components originating directly from theoxidation reaction product mixture, the cleavage reaction mixture mayfurther comprise other added materials, such as the cleavage catalyst, asolvent, and one or more products of the cleavage reaction such asphenol and cyclohexanone recycled from the cleavage product mixture, orfrom a downstream separation step. Thus, the cleavage reaction mixtureinside the cleavage reactor may comprise, based on the total weight ofthe cleavage reaction mixture: (i) phenol at a concentration from CPh9wt % to CPh10 wt %, where CPh9 and CPh10 can be, independently: 20, 25,30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80, as long as CPh9<CPh10;(ii) cyclohexanone at a concentration from Cch1 wt % to Cch2 wt %, whereCch1 and Cch2 can be, independently: 20, 25, 30, 35, 40, 45, 50, 55, 60,65, 70, 75, or 80, as long as Cch1<Cch2; and (iii) cyclohexylbenzene ata concentration from Cchb7 wt % to Cchb8 wt %, where Cchb7 and Cchb8 canbe, independently: 5, 8, 9, 10, 12, 14, 15, 18, 20, 22, 24, 25, 26, 28,30, 35, 40, 45, 50, 55, 60, 65, 70, as long as Cchb7<Cchb8.

The reactor used to effect the cleavage reaction (i.e., the cleavagereactor) may be any type of reactor known to those skilled in the art.For example, the cleavage reactor may be a simple, largely open vesseloperating in a near-continuous stirred tank reactor mode, or a simple,open length of pipe operating in a near-plug flow reactor mode. Thecleavage reactor may comprise a plurality of reactors in series, eachperforming a portion of the conversion reaction, optionally operating indifferent modes and at different conditions selected to enhance thecleavage reaction at the pertinent conversion range. The cleavagereactor can be a catalytic distillation unit.

The cleavage reactor can be operable to transport a portion of thecontents through a cooling device and return the cooled portion to thecleavage reactor, thereby managing the exothermicity of the cleavagereaction. Alternatively, the reactor may be operated adiabatically.Cooling coils operating within the cleavage reactor(s) can be used to atleast a part of the heat generated.

The cleavage product mixture exiting the cleavage reactor may comprise,based on the total weight of the cleavage product mixture: (i) phenol ata concentration from CPh11 wt; to CPh12 wt %, where CPh11 and CPh12 canbe, independently: 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or80, as long as Ch11<CPh2; (ii) cyclohexanone at a concentration fromCch3 wt %, to Cch4 wt %, where Cch3 and Cch4 can be, independently: 20,25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80, as long as Cch3<Cch4;and (iii) cyclohexylbenzene at a concentration from Cchb9 wt % to Cchb10wt %, where Cchb9 and Cchb10 can be, independently: 5, 8, 9, 10, 12, 14,15, 18, 20, 22, 24, 25, 26, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, aslong as Cchb9<Cchb10.

As discussed above, the cleavage product mixture may comprise one ormore contaminants. In embodiments disclosed herein, the processesfurther comprise contacting at least a portion of a contaminant with anacidic material to convert at least a portion of the contaminant to aconverted contaminant, thereby producing a modified product mixture.Detailed description of the contaminant treatment process can be found,e.g., in International Publication WO 2012/036822A1, the relevantcontent of which is incorporated herein by reference in its entirety.

At least a portion of the cleavage product mixture may be subjected to aneutralization reaction. Where a liquid acid such as sulfuric acid isused as the cleavage catalyst, it is highly desirable that the cleavagereaction product is neutralized by a base, such as an organic amine(e.g., methylamine, ethylamine, diamines such as methylenediamine,propylene diamine, butylene diamine, pentylene diamine, hexylenediamine, and the like) before the mixture is subjected to separation toprevent equipment corrosion by the acid. Desirably, the thus formedamine sulfate salt has a boiling point higher than that ofcyclohexylbenzene.

Separation and Purification

A portion of the neutralized cleavage reaction product can then beseparated by methods such as distillation. In one example, in a firstdistillation column after the cleavage reactor, a heavies fractioncomprising the amine salt is obtained at the bottom of the column, aside fraction comprising cyclohexylbenzene is obtained in the middlesection, and an upper fraction comprising cyclohexanone, phenol,methylcyclopentanone, and water is obtained.

The separated cyclohexylbenzene fraction can then be treated and/orpurified before being delivered to the oxidizing step. Since thecyclohexylbenzene separated from the cleavage product mixture maycontain phenol and/or olefins such as cyclohexenylbenzene, the materialmay be subjected to treatment with an aqueous composition comprising abase as described above for the second fraction of the oxidation productmixture and/or a hydrogenation step as disclosed in, for exampleInternational Patent Application No. WO 2011/100013A1, the entirecontents of which are incorporated herein by reference.

In one example, the fraction comprising phenol, cyclohexanone, and watercan be further separated by simple distillation to obtain an upperfraction comprising primarily cyclohexanone and methylcyclopentanone anda lower stream comprising primarily phenol, and some cyclohexanone.Cyclohexanone cannot be completely separated from phenol without usingan extractive solvent due to an azeotrope formed between these two.Thus, the upper fraction can be further distillated in a separate columnto obtain a pure cyclohexanone product in the vicinity of the bottom andan impurity fraction in the vicinity of the top comprising primarilymethylcyclopentanone, which can be further purified, if needed, and thenused as a useful industrial material. The lower fraction can be furtherseparated by a step of extractive distillation using an extractivesolvent (e.g., glycols such as ethylene glycol, propylene glycol,diethylene glycol, triethylene glycol, and the like) described in, e.g.,co-assigned, co-pending patent applications WO 2013/165656A1 and WO2013/165659, the contents of which are incorporated herein by referencein their entirety. An upper fraction comprising cyclohexanone and alower fraction comprising phenol and the extractive solvent can beobtained. In a subsequent distillation column, the lower fraction canthen be separated to obtain an upper fraction comprising a phenolproduct and a lower fraction comprising the extractive solvent.

Separation and Hydrogenation

At least a portion, preferably the whole, of the neutralized cleavageeffluent (cleavage reaction product) may be separated and aphenol-containing fraction thereof can be hydrogenated to covert aportion of the phenol to cyclohexanone in accordance with the presentinvention. Examples of the separation and hydrogenation process and/orsystem are illustrated in the attached drawings and described in detailbelow.

It should be understood that process and/systems shown in the schematic,not-to-scale drawings are only for the purpose of illustrating thegeneral material and/or heat flows and general operating principles. Tosimplify illustration and description, some routine components, such aspumps, valves, reboilers, pressure regulators, heat exchangers,recycling loops, condensers, separation drums, sensors, rectifiers,fillers, distributors, stirrers, motors, and the like, are not shown inthe drawings or described herein. One having ordinary skill in the art,in light of the teachings herein, can add those components whereappropriate.

FIG. 1 is a schematic diagram showing an exemplary process/system 101 ofthe present disclosure for making cyclohexanone from a mixturecomprising phenol, cyclohexanone and cyclohexylbenzene including aprimary fractionation column T1 (i.e., the first distillation column), ahydrogenation reactor R1, and a cyclohexanone purification column T2(i.e., the second distillation column). Feed 103 from storage S1,comprising phenol, cyclohexanone, and cyclohexylbenzene, is fed into theprimary fractionation column T1.

Feed 103 can be produced from any method. A preferred method is bycleaving a cyclohexylbenzene hydroperoxide in the presence of an acidcatalyst such as H₂SO₄ and cyclohexylbenzene as described above. Feed103 may further comprise impurities other than cyclohexylbenzene suchas: light components such as water, methylcyclopentanone, pentanal,hexanal, benzylic acid, and the like, and heavy components such asmethylcyclopentylbenzene, bicyclohexane, sulfate of an organic amine(such as 1,6-hexamethylenediame, 2-methyl-1,5-pentamethylenediamine,ethylenediamine, propylenediamine, diethylenetriamine, and the like)produced by injecting the amine into the cleavage mixture to neutralizethe liquid acid catalyst used. Feed 103 may further comprise olefinssuch as phenylcyclohexene isomers, hydroxylcyclohexanone, cyclohexenone,and the like. The cyclohexylbenzene hydroperoxide may be produced byaerobic oxidation of cyclohexylbenzene in the presence of a catalystsuch as NHPI as described above. The cyclohexylbenzene may be producedby hydroalkylation of benzene in the presence of ahydrogenation/alkylation bi-functional catalyst as described above.

Thus, feed 103 (the first mixture) may comprise, based on the totalweight thereof:

-   -   cyclohexanone at a concentration of Cxnone(FM1) in a range from        x11 wt % to x12 wt %, where x11 and x12 can be, independently:        10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 82,        84, 85, 86, 88, or 90, as long as x11<x12; preferably, 20 wt        %≦Cxnone(FM1)≦30 wt %;    -   phenol at a concentration of Cphol(FM1) in a range from x21 wt %        to x22 wt %, where x21 and x22 can be, independently: 10, 15,        20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 82, 84, 85,        86, 88, or 90, as long as x21<x22; preferably, 20 wt        %≦Cphol(FM1)≦30 wt %; preferably,        0.3≦Cxnone(FM1)/Cphol(FM1)≦2.0; more preferably        0.5≦Cxnone(FM1)/Cphol(FM1)≦1.5; even more preferably        0.8≦Cxnone(FM1)/Cphol(FM1)≦1.2;    -   cyclohexylbenzene at a concentration of Cchb(FM1) in a range        from x31 wt % to x32 wt %, where x31 and x32 can be,        independently: 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4,        5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28,        30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, 50, 52, 54, 55,        56, 58, 60, 62, 64, 65, 66, 68, 70, 72, 74, 75, 76, 77, 78, 79,        or 80, as long as x31<x32; preferably 30 wt %≦Cchb(FM1)≦60 wt %;        and    -   bicyclohexane at a concentration of Cbch(FM1) in a range from        x41 W/o to x42 wt %, based on the total weight of the first        mixture, where x41 and x42 can be, independently: 0, 0.00001,        0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4,        5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28,        or 30, as long as x41<x42; preferably, 0.001 wt %≦Cbch(FM1)≦1 wt        %.

From the primary fractionation column T1, a first upper effluent 105comprising cyclohexanone and light components such as water,methylcyclopentanone, and the like, is produced in the vicinity of thetop of the column T1. Effluent 105 may comprise, based on the totalweight thereof:

-   -   cyclohexanone at a concentration of Cxnone(UE1), where z11 wt        %≦Cxnone(UE1)≦z12 wt %, z11 and z12 can be, independently: 60,        65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99,        99.5, or 99.9, as long as z11<z12; preferably 75≦Cxnone(UE1)≦95;    -   phenol at a concentration of Cphol(UE1), where        z21≦Cphol(UE1)≦z22, z21 and z22 can be, independently: 0,        0.00001, 0.00005, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05, 0.1,        0.5, or 1, as long as z21≦z22;    -   cyclohexylbenzene at a concentration of Cchb(UE1), where y31 wt        %≦Cchb(UE1)≦y32 wt %, where y31 and y32 can be, independently:        0, 0.0001, 0.00005, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05,        0.1, 0.5, or 1, as long as y31<y32;    -   bicyclohexane at a concentration of Cbch(UE1), where y41 wt        %≦Cbch(UE1)≦y42 wt %, y41 and y42 can be, independently: 0,        0.00001, 0.00005, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.05, 0.1,        0.5, or 1, as long as y41<y42; and    -   cyclohexanol at a concentration of Cxnol(UE1), where x51 wt        %≦Cxnol(UE1)≦x52 wt %, based on the total weight of the first        upper effluent, where x51 and x52 can be, independently: 0.001,        0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0,        4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10, as        long as x51<x52; preferably 0.1 wt %≦Cxnol(UE1)≦5.0 wt %.

The first upper effluent 105 is then sent to a cyclohexanonepurification column T2, from which a third upper effluent 121 comprisinglight components such as water, methylcyclopentanone, and the like, isproduced at a location in the vicinity of the top of column T2 and thendelivered to storage S5. A second upper effluent 123 comprisingessentially pure cyclohexanone is produced and sent to storage S7. Inthe vicinity of the bottom of column T2, a second lower effluent 125 isproduced and delivered to storage S9. The second lower effluent can be,e.g., a KA oil comprising both cyclohexanone and cyclohexanol. Thus, thesecond upper effluent 123 may comprise, based on the total weightthereof, cyclohexanone at a concentration of Cxnone(UE2), whereCxnone(UE2)≧y11 wt %, y11 can be 95, 95.5, 96, 96.5, 97, 97.5, 98, 98.5,99, 99.5, 99.8, or 99.9. The second lower effluent 125 may comprise,based on the total weight thereof: cyclohexanol at a concentration ofCxnol(LE2), y51 wt %≦Cxnol(LE2)≦y52 wt %, y51 and y52 can be,independently: 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32,34, 35, 36, 38, 40, 42, 44, 45, 46, 48, 50, 52, 54, 55, 56, 58, 60, 62,64, 65, 66, 68, 70, 72, 74, 75, 76, 78, or 80, as long as y51<y52; andcyclohexanone at a concentration of Cxnone(LE2), e11 wt %≦Cxnol(LE2)≦e12wt %, e11 and e12 can be, independently: 10, 12, 14, 15, 16, 18, 20, 22,24, 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, 50, 52,54, 55, 56, 58, 60, 62, 64, 65, 66, 68, 70, 72, 74, 75, 76, 78, or 80,as long as e11<e12.

The first middle effluent 107 produced from the primary fractionationcolumn T1 comprises phenol at a concentration higher than in feed 103and higher than in the first upper effluent 105, cyclohexanone at aconcentration lower than in both feed 103 and the first upper effluent105, cyclohexylbenzene at a concentration desirably lower than in feed103 and higher than in the first upper effluent 105, and one or more ofother impurities such as bicyclohexane and cyclohexenone. Thus, effluent107 may comprise, based on total weight thereof:

-   -   cyclohexanone at a concentration of Cxnone(ME1), where all wt        %≦Cxnone(ME1)≦a12 wt %, a11 and a12 can be, independently: 1, 2,        4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30,        35, 40, 45, or 50, as long as a11<a12;    -   phenol at a concentration of Cphol(ME1), where a21 wt        %≦Cphol(ME1)≦a22 wt %, based on the total weight of the first        middle effluent, where a21 and a22 can be, independently: 10,        15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, as long        as a21<a22; preferably, 1.0≦Cphol(ME1)/Cxnone(ME1)≦3.0; more        preferably, 2.0≦Cphol(ME1)/Cxnone(ME1)≦3.0, close to the ratio        in a phenol/cyclohexanone azeotrope;    -   cyclohexylbenzene at a concentration of Cchb(ME1), where a31 wt        %≦Cchb(ME1)≦a32 wt %, a31 and a32 can be, independently: 0.001,        0.005, 0.01, 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6,        8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, or 30, as        long as a31<a32;    -   bicyclohexane at a concentration of Cbch(ME1), where a41 wt        %≦Cbch(ME1)≦a42 wt %, a41 and a42 can be, independently: 0.001,        0.005, 0.01, 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6,        8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, or 30, as        long as a41<a42; and    -   cyclohexanol at a concentration of Cxnol(ME1), where a51 wt        %≦Cbch(ME1)≦a52 wt %, a51 and a52 can be, independently: 0.01,        0.02, 0.04, 0.05, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1,        2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28,        or 30, as long as a5<a52; preferably 0.01 wt %≦Cxnol(ME1)≦5 wt        %.

Effluent 107 is delivered to a hydrogenation reactor R1, where it ismixed with a hydrogen gas feed 112 comprising fresh make-up hydrogenstream 111 from storage S3 and recycle hydrogen 117. The phenolcontained in feed 107 and hydrogen reacts with each other in thepresence of a catalyst bed 113 inside reactor R1 to producecyclohexanone. Some of the cyclohexanone inside the reactor R1 reactswith hydrogen in the presence of the catalyst bed 113 as well to producecyclohexanol. In the exemplary process shown in FIG. 1, surplus hydrogenis fed into reactor R1. It is contemplated that a secondphenol-containing stream (not shown), separate from and independent ofeffluent 107, may be fed into the hydrogenation reactor R1. Suchadditional feed can advantageously contain phenol at a concentration ofCphol(FP), d21 wt %≦Cphol(FP)≦d22 wt %, based on the total weight of thesecond phenol-containing stream, where d21 and d22 can be,independently: 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95,96, 97, 98, 99, or 100, as long as d21<d22. Preferably, the secondphenol-containing stream is a substantially pure phenol produced by anyprocess, such as the conventional cumene process, coal processes, andthe like.

The total feed, including stream 107 and optional additional streams,delivered to the hydrogenation reactor R1, if blended together beforebeing fed into R1, may have an overall composition containing phenol ata concentration of Cphol(A), cyclohexanone at a concentration ofCxnone(A), cyclohexylbenzene at a concentration of Cchb(A), andbicyclohexane at a concentration of Cbch(A), wherein the concentrationsare in the following ranges, based on the total weight of thehydrogenation feed:

-   -   a1 wt %≦Cxnone(A)≦a2 wt %, where a1 and a2 can be,        independently: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,        2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28,        30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, 50, as long as        a1<a2;    -   b1 wt %≦Cphol(A)≦b2 wt %, where b1 and b2 can be, independently:        10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 82,        84, 85, 86, 88, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99, as        long as a21<a22;    -   c1 wt %≦5 Cchb(A)≦c2 wt %, where c1 and c2 can be,        independently: 0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.4, 0.5,        0.6, 0.8, 1, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24,        25, 26, 28, or 30, as long as c1<c2; preferably, 1 wt        %≦Cchb(A)≦20 wt %; and    -   d1 wt %≦Cbch(A)≦d2 wt %, where d1 and d2 can be, independently:        0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4,        5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, or 30,        as long as d1<d2; preferably, 1 wt %≦Cbch(A)≦20 wt %.

In the hydrogenation reaction zone, the following reactions can takeplace, resulting in an increase of the concentrations of cyclohexanone,cyclohexanol, and bicyclohexane, and a decrease of the concentrations ofphenol, cyclohexenone and cyclohexylbenzene:

Cyclohexanone may hydrogenate to make cyclohexanol in the hydrogenationreactor R1. Because the net effect of the reaction is an overallincrease of cyclohexanone, this reaction is not included in the aboveparagraph. Nonetheless, cyclohexanone can engage in competition againstphenol for hydrogen, which should be reduced or inhibited.

The total amount of hydrogen, including fresh, make-up hydrogen andrecycled hydrogen, fed into the reactor R1 and the total amount ofphenol fed into the hydrogenation reaction zone, desirably exhibit ahydrogen to phenol molar ratio of R(H2/phol), where R1≦R(H2/phol)≦R2, R1and R2 can be, independently: 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5,5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10, as long R1<R2.While a higher R(H2/phol) ratio can result in higher overall conversionof phenol, it tends to result in higher conversion of cyclohexanone,higher selectivity of phenol to cyclohexanol, and higher conversion ofcyclohexylbenzene, as well. Therefore, it has been found that, it isgenerally desirable that in the hydrogenation reactor R1, the reactionconditions, including but not limited to temperature, pressure, andR(H2/phol) ratio, and catalysts, are chosen such that the overallconversion of phenol is not too high.

The hydrogenation reactions take place in the presence of ahydrogenation catalyst. The hydrogenation catalyst may comprise ahydrogenation metal performing a hydrogenation function supported on asupport material. The hydrogenation metal can be, e.g., Fe, Co, Ni, Ru,Rh, Pd, Ag, Re, Os, Ir, and Pt, and mixtures and combinations of one ormore thereof. The support material can be advantageously an inorganicmaterial, such as oxides, glasses, ceramics, molecular sieves, and thelike. For example, the support material can be activated carbon, Al₂O₃,Ga₂O₃, SiO₂, GeO₂, SnO, SnO₂, TiO₂, ZrO₂, Sc₂O₃, Y₂O₃, alkali metaloxides, alkaline earth metal oxides, and mixtures, combinations,complexes, and compounds thereof. The concentration of the hydrogenationmetal can be, e.g., in a range from Cm1 wt % to Cm2 wt %, based on thetotal weight of the catalyst, where Cm1 and Cm2 can be, independently:0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0,4.5, 5.0, as long as Cm1<Cm2.

Without intending to be bound by any particular theory, it is believedthat the above hydrogenation reactions occur quickly in the presence ofthe hydrogenation metal. Therefore, it is highly desirable that thehydrogenation metal is preferentially distributed in the outer rim ofthe catalyst particles, i.e., the concentration of the hydrogenationmetal in the catalyst particle surface layer is higher than in the corethereof. Such rimmed catalyst can reduce the overall hydrogenation metalloading, reducing cost thereof, especially if the hydrogenation metalcomprises a precious metal such as Pt, Pd, Ir, Rh, and the like. The lowconcentration of hydrogenation metal in the core of the catalystparticle also leads to lower chance of hydrogenation of cyclohexanone,which may diffuse from the surface to the core of the catalystparticles, resulting in higher selectivity of cyclohexanone in theoverall process.

It is believed that the catalyst surface can have different degrees ofadsorption affinity to the different components in the reaction mediasuch as phenol, cyclohexanone, cyclohexanol, cyclohexenone,cyclohexylbenzene, and bicyclohexane. It is highly desired that thecatalyst surface has higher adsorption affinity to phenol than tocyclohexanone and cyclohexylbenzene. Such higher phenol adsorptionaffinity will give phenol competitive advantages in the reactions,resulting in higher selectivity to cyclohexanone, lower selectivity ofcyclohexanol, and lower conversion of cyclohexylbenzene, which are alldesired in a process designed for making cyclohexanone. In addition, inorder to favor the conversion of phenol to cyclohexanone over theconversion of cyclohexylbenzene to bicyclohexane and the conversion ofcyclohexanone to cyclohexanol, it is highly desired that the phenolconcentration in the reaction medium in the hydrogenation reactor R1 isrelatively high, so that phenol molecules occupy most of the activecatalyst surface area. Therefore, it is desired that the overallconversion of phenol in the reactor R1 is relatively low.

As such, it is desired that in the hydrogenation reactor R1, theselectivity of phenol to cyclohexanone is Sel(phol)a, the selectivity ofphenol to cyclohexanol is Sel(phol)b, and at least one of the followingconditions (i), (ii), (iii), and (iv) is met:

30%≦Con(phol)≦95%;  (i)

0.1%≦Con(chb)≦20%;  (ii)

80%≦Sel(phol)a≦99.9%; and  (iii)

0.1%≦Sel(phol)b≦20%.  (iv)

The feed(s) to the hydrogenation reactor R1 may further comprisecyclohexenone at a concentration of Cxenone(A), where e1 wt%≦Cxenone(A)≦e2 wt %, based on the total weight of the hydrogenationfeed, e1 and e2 can be, independently: 0.01, 0.02, 0.03, 0.04, 0.05,0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,1.5, 2, 2.5, 3.5, 4, 4.5, or 5, as long as e1<e2. It is highly desiredthat in step (B), the conversion of cyclohexenone is Con(xenone),Con5%≦Con(xenone)≦Con6%, where Con5 and Con6 can be, independently: 85,86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, as long asCon5<Con6. Thus, a great majority of the cyclohexenone contained in thefeed(s) is converted into cyclohexanone in the hydrogenation reactor R1.

At the bottom of reactor R1, a hydrogenation reaction product stream 115comprising phenol at a concentration lower than in stream 107,cyclohexanone at a concentration higher than in stream 107,cyclohexylbenzene, bicyclohexane, and surplus hydrogen is taken. Stream115 may comprise, based on the total weight thereof:

-   -   Cyclohexanone at a concentration of Cxnone(HRP), where b11 wt        %≦Cxnone(HRP)≦b12 wt %, b11 and b12 can be, independently: 20,        25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, as long        as b11<b12;    -   Phenol at a concentration of Cphol(HRP), where b21 wt        %≦Cphol(HRP)≦b22 wt %, b21 and b22 can be, independently: 1, 2,        5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 40,        50, as long as b21<b22;    -   cyclohexylbenzene at a concentration of Cchb(HRP), where b31 wt        % 5 Cchb(HRP)≦b32 wt %, b31 and b32 can be, independently:        0.001, 0.005, 0.01, 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4,        5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, as        long as b31<b32;    -   bicyclohexane at a concentration of Cbch(HRP), where b41 wt        %≦Cbch(HRP)≦b42 wt %, b41 and b42 can be, independently: 0.001,        0.005, 0.01, 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 2, 4, 5, 6,        8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, as long        as b41<b42; and    -   cyclohexanol at a concentration of Cxnol(HRP), where b51 wt        %≦Cxnol(HRP)≦b52 wt %, b51 and b52 can be, independently: 0.01,        0.02, 0.04, 0.05, 0.06, 0.08, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1,        2, 4, 5, 6, 8, 10, as long as b51<b52.

Preferably, at least one of the following criteria is met in thehydrogenation reaction product stream 115:

-   -   Ra31≦Cchb(ME1)/Cchb(HRP)≦Ra32, where Ra31 and Ra32 can be,        independently: 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75,        0.80, 0.85, 0.90, 0.92, 0.94, 0.95, 0.96, 0.98, 1.00, 1.02,        1.04, 1.05, 1.06, 1.08, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35,        1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.00, 3.00, 4.00, 5.00,        6.00, 7.00, 8.00, 9.00, or 10.0, as long as Ra31<Ra32; more        preferably, 0.80≦Cchb(ME1)/Cchb(HRP)≦1.00, meaning that        cyclohexylbenzene concentration does not decrease significantly        in the hydrogenation reaction zone;    -   Ra41≦Cbch(HRP)/Cbch(ME1)≦Ra42, where Ra41 and Ra42 can be,        independently: 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75,        0.80, 0.85, 0.90, 0.92, 0.94, 0.95, 0.96, 0.98, 1.00, 1.02,        1.04, 1.05, 1.06, 1.08, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35,        1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.00, 3.00, 4.00, 5.00,        6.00, 7.00, 8.00, 9.00, or 10.0, as long as Ra41<Ra42;        preferably, 1.0≦Cbch(HRP)/Cbch(ME1)≦1.5, meaning that        bicyclohexane concentration does not increase significantly in        the hydrogenation reaction zone; and    -   Ra51≦Cxnol(HRP)/Cxnol(ME1)≦Ra52, where Ra51 and Ra52 can be,        independently: 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.75,        0.80, 0.85, 0.90, 0.92, 0.94, 0.95, 0.96, 0.98, 1.00, 1.02,        1.04, 1.05, 1.06, 1.08, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35,        1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 2.00, 3.00, 4.00, 5.00,        6.00, 7.00, 8.00, 9.00, or 10.0, as long as Ra51<Ra52;        preferably, 1.0≦Cxnol(HRP)/Cxnol(ME1)≦1.5, meaning that        cyclohexanol concentration does not increase significantly in        the hydrogenation reaction zone.

Stream 115 is then delivered to a separation drum D1, where a vaporphase comprising a majority of the surplus hydrogen and a liquid phaseis obtained. The vapor phase can be recycled as stream 117 to reactor R1as part of the hydrogen supply, and the liquid phase 119 is recycled tothe primary fractionation column T1 at one or more side locations oncolumn T1, at least one of which is above the location where the firstmiddle effluent 107 is taken, but below the location where the firstupper effluent 105 is taken.

The first bottom effluent 109 obtained from the primary fractionationcolumn T1 comprises primarily heavy components such ascyclohexylbenzene, bicyclohexane, amine salts mentioned above, C18+, C12oxygenates, and C18+ oxygenates. This fraction is delivered to a heaviesdistillation column T3 (the third distillation column), from which athird upper effluent 127 desirably comprising cyclohexylbenzene at aconcentration higher than C31 wt % and a lower effluent 129 areproduced, where C31 can be 80, 82, 84, 85, 86, 88, 90, 92, 94, 95, 96,98, or 99. Effluent 127 may be delivered to storage S11 and effluent 129to storage S13. Effluent 127 may further comprise olefins, primarilyphenylcyclohexene isomers, at a non-negligible amount. It may bedesirable to subject effluent 127 to hydrogenation to reduce olefinconcentrations, and subsequently recycle the hydrogenated effluent 127to an earlier step such as cyclohexylbenzene oxidation to convert atleast a portion of it to cyclohexylbenzene hydroperoxide, such that theoverall yield of the process is improved.

FIG. 2 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to the process/systemshown in FIG. 1, but comprising modified fluid communications betweenand/or within the primary fractionation column T1 and the hydrogenationreactor R1. In this figure, the hydrogenation reaction product 115comprises residual hydrogen, as in the example shown in FIG. 1. Effluent115 is first delivered into separation drum D1, where a hydrogen-richvapor stream 117 a is obtained, compressed by a compressor 118, and thendelivered to reactor R1 as a stream 117 b together with fresh, make-uphydrogen stream 111 into reactor R1. A liquid stream 119 is obtainedfrom separation drum D1, then divided into multiple streams (two recyclestreams, a first liquid product stream 119 b and a second liquid productstream 119 a, shown in FIG. 2), recycled to two different locations onthe side of column T1, one below the location where the first middleeffluent 107 is taken (shown at approximately the same level as feed103), and the other above the location where the first middle effluent107 is drawn. It is also possible that the first liquid product stream119 b is recycled to a different location on the primary fractionationcolumn T1, as long as it is not lower than the location where the firstmiddle effluent 107 is drawn, and lower than the location where thefirst upper effluent 105 is drawn. It is also possible that the secondliquid product stream 119 a is recycled to a slight different locationon T1, as long as it is lower than the location where the first middleeffluent 105 is drawn. For example, the second liquid product stream 119a may be fed into the primary fractionation column T1 at a locationbetween the location where the first mixture is fed and the locationwhere the first middle effluent is drawn, with a distance of at most k Dfrom the location where the first mixture is fed, where D is the totaldistance from the location where the first mixture is fed and thelocation where the first middle effluent is drawn, and k can be, e.g.,0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, 0.10, 0.05. In theembodiment shown in FIG. 2, the two liquid product streams 119 a and 119b are divided from a single liquid stream 119 from the separation drumD1, and therefore have substantially the same composition. However, itis also possible that the chemical compositions of 119 a and 119 b maydiffer slightly, e.g., if they are directly derived from the separationdrum D1 at different locations.

This modified recycle fluid communication shown in FIG. 2 (alsosimilarly illustrated partly in FIGS. 4, 5, 6, and 8) betweenhydrogenation reactor R1 and the primary fractionation column T1compared to FIG. 1 has surprising advantages. It was found that wherethe recycle liquid stream 119 is fed to one location only, such as at alocation above the first middle effluent 107, bicyclohexane iscontinuously produced in reactor R1 from the cyclohexylbenzene in stream107, and then may steadily accumulate in column T1 to such highconcentration that a separate phase can form, interfering with effectiveproduct separation in column T1. On the other hand, where the recyclestream 119 is recycled back to column T1 at multiple locations on T1 (asshown in FIG. 2), the probability of forming a separate bicyclohexanephase inside T1 is drastically reduced or eliminated.

Another advantage of recycling the liquid product streams to the primaryfractionation column at multiple, different locations as illustrated inFIG. 2 is the suppression of the formation of bicyclohexane in thehydrogenation reactor R1 due to cyclohexylbenzene hydrogenation. Withoutintending to be bound by any particular theory, it is believed that byfeeding the second liquid product stream to the primary fractionationcolumn at a location lower than the first middle effluent, part of thebicyclohexane in the hydrogenation reaction product will invariably makeits way into the first middle effluent and then into the hydrogenationreaction R1. The presence of bicyclohexane in the hydrogenation feedwill likely suppress the hydrogenation of cyclohexylbenzene to makeadditional bicyclohexane. It is possible that once the operation reachesa steady state, the concentrations of bicyclohexane in the hydrogenationfeed and in the hydrogenation reaction product can be very close,meaning that very little, if any, cyclohexylbenzene is converted intobicyclohexane in the hydrogenation reactor. This is a highly desirableresult, given that bicyclohexane produced in the process will likelyhave to be discarded or burned as waste, resulting in irretrievableyield loss.

The quantity of the recycle liquid product in streams 119 a and 119 bmay be the same or different. Preferably, the quantity (e.g., flow rate)of the first liquid product stream 119 b is higher than the quantity ofthe second liquid product stream 119 a. For example, the ratio of theweight of the first liquid stream 119 b to the weight of the secondliquid stream 119 a can be in a range from r1 and r2, where r1 and r2can be, independently, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9,2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5,9.0, 9.5, 10, 15, 20, 25, 30, 35, 40, 45, or 50, as long as r1<r2.Preferably r1=1.0 and r2=5.0. Thus, even if the quantity of the secondliquid product stream 119 a is significantly smaller than the quantityof the first liquid product stream 119 b, the introduction of 119 b,which comprises cyclohexanone at a higher concentration than the firstmiddle effluent 107, at a location lower than the first middle effluent107, serves the purpose of reducing or eliminating the possibility ofthe accumulation of bicyclohexane in the primary fractionation column T1to a level that a phase separation may occur. Feeding too much of theliquid product stream to a location below the first middle effluent mayreduce the overall energy efficiency of the primary fractionation columnT1 slightly. This is why it is preferred that the quantity of the firstliquid product stream is larger than the quantity of the second liquidproduct stream.

The bicyclohexane concentration in the hydrogenation product to thebicyclohexane concentration in the first middle effluent can be in arange from r3 to r4, where r3 and r4 can be, independently: 1.0, 1.1,1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.2, 2.4, 2.5, 2.6, 2.8,3.0, 3.2, 3.4, 3.5, 3.6, 3.8, 4.0, 4.2, 4.4, 4.5, 4.6, 4.8, or 5.0, aslong as r3<r4. Preferably, r3=1.0, and r4=1.5.

FIG. 3 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1 and 2 comprising modified fluid communications and/or heat transferarrangement between and/or within the primary fractionation column T1and the cyclohexanone purification column T2. In this figure, thehydrogenation reactor R1 and its peripheral equipment are not shown. Inthis example, the first middle effluent 107 drawn from column T1 isdivided into multiple streams (two streams 107 a and 107 b shown), oneof which (107 a) is delivered to the hydrogenation reactor R1 (notshown) as hydrogenation feed, and the other (107 b) to a heat exchanger131 in fluid and thermal communication with the cyclohexanonepurification column T2. In this example, the bottom stream 125 (e.g.,comprising a mixture of cyclohexanone and cyclohexanol) from column T2is divided into three streams: stream 135 which passes through heatexchanger 131 and is heated by stream 107 b; stream 139 which is heatedby a heat exchanger 141 and then recycled to column T2; and stream 145,which is delivered to storage S9 via pump 147. Stream 107 b becomes acooler stream 133 after passing through heat exchanger 131, and is thensubsequently recycled to primary fractionation column T1 at one or morelocations, at least one of which is located above the location where thefirst middle effluent 107 is drawn. A heat management scheme asillustrated in FIG. 3 can significantly improve the energy efficiency ofthe overall process and system of the present disclosure.

FIG. 4 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1-3, but comprising a tubular heat exchanger-type hydrogenation reactor.This figure illustrates an example where the hydrogenation reactor R1operates under hydrogenation conditions such that a majority of thephenol and/or cyclohexylbenzene present in the reaction media inside thereactor R1 are in vapor phase. In this example, the first middleeffluent 107 taken from the primary fractionation column T1 is firstcombined with hydrogen feeds (including fresh make-up hydrogen stream111 and recycle hydrogen stream 117 b), heated by a heat exchanger 153and then delivered to a tubular heat-exchanger type hydrogenationreaction R1 having hydrogenation catalyst installed inside the tubes157. A stream of cooling media 159 such as cold water supplied fromstorage S11 passes through the shell of the exchanger/reactor R1 andexits the reactor R1 as a warm stream 161 and is then delivered tostorage S13, thereby a significant amount of heat released from phenolhydrogenation reaction is carried away, maintaining the temperatureinside the reactor R1 in a range from T1° C. to T2° C., and an absolutepressure inside the reactor R1 in a range from P1 kPa to P2 kPa where T1and T2 can be, independently: 140, 145, 150, 155, 160, 165, 170, 175,180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 250,260, 270, 280, 290, 300, as long as T1<T2, and P1 and P2 can be,independently: 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200,250, 300, 350, or 400, as long as P1<P2. Preferably T2=240 and P2=200.Alternatively, the cooling medium may comprise at least a portion of thehydrogenation feed in liquid phase, such that at least a portion of thefeed is vaporized, and at least a portion of the vapor feed is then fedto the hydrogenation reactor R1.

Because heat transfer of vapor phase is not as efficient as liquidphase, and the phenol hydrogenation reaction is highly exothermic, it ishighly desired that heat transfer is carefully managed in such vaporphase hydrogenation reactor. Other types of reactors suitable for aliquid phase reaction can be used as well. For example, fixed-bedreactors configured to have intercooling capability and/or quenchingoptions, so that the heat generated in the reaction can be taken awaysufficiently quickly to maintain the reaction media in a desirabletemperature range.

FIG. 5 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1-4, but comprising three fixed bed hydrogenation reactors R3, R5, andR7 connected in series. This figure illustrates an example where thehydrogenation reactors operate under hydrogenation conditions such thata majority of the phenol and/or cyclohexylbenzene present in thereaction media inside the reactors R3, R5, and R7 are in liquid phase.In this example, the first middle effluent 107 taken from the primaryfractionation column T1 is first combined with hydrogen feeds (includingfresh make-up hydrogen stream 111 and recycle hydrogen stream 117 b) toform a feed stream 151, then heated by a heat exchanger 153, and thendelivered as stream 155 to a first hydrogenation reactor R3 having acatalyst bed 167 inside. A portion of the phenol is converted tocyclohexanone in reactor R3, releasing a moderate amount of heat raisingthe temperature of the reaction media. Effluent 169 exiting reactor R3is then cooled down by heat exchanger 171, and then delivered into asecond fixed bed reactor R5 having a catalyst bed 175 inside. A portionof the phenol contained in the reaction media is converted tocyclohexanone in reactor R5, releasing a moderate amount of heat raisingthe temperature inside the reactor R5. Effluent 177 exiting reactor R5is then cooled down by heat exchanger 179, and then delivered to a thirdfixed bed hydrogenation reactor R7 having a catalyst bed 183 inside. Aportion of the phenol contained in the reaction media is converted tocyclohexanone in reactor R7, releasing a moderate amount of heat raisingthe temperature inside the reactor R7. Effluent 185 exiting reactor R7is then cooled down by heat exchanger 187, and delivered to drum D1,where a vapor phase 117 a and a liquid phase 119 are obtained. By usingmultiple reactors in the hydrogenation reaction zone, and the use ofheat exchangers between and after each reactor, temperatures inside thereactors R3, R5, and R7 are each independently maintained in a rangefrom T3° C. to T4° C., and the absolute pressures inside reactors R3,R5, and R7 are each independently maintained in a range from P3 kPa toP4 kPa, where T3 and T4 can be, independently: 140, 145, 150, 155, 160,165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230,235, 240, 250, 260, 270, 280, 290, 300, as long as T3<T4, and P3 and P4can be, independently: 375, 400, 425, 450, 475, 500, 525, 550, 575, 600,625, 650, 675, 700, 725, 750, 775, 800, 825, 850, 875, 900, 925, 950,975, 1000, 1025, 1050, 1075, 1100, 1125, 1134, 1150, 1175, 1200, as longas P3<P4. Preferably, T4=240 and P4=1134. In general, higher temperaturefavors the production of cyclohexanol over cyclohexanone. Thus, it ishighly desirable that the hydrogenation is conducted at a temperature nohigher than 220° C.

FIG. 6 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to the process/systemshown in FIGS. 1-5, but comprising modified fluid communications betweenand/or within the primary fractionation column T1 and the hydrogenationreactor R1. In this figure, two middle effluents, including a firstmiddle effluent 107 a and a second middle effluent 107 b, are drawn fromthe side of the primary fractionation column T1. The two effluents 107 aand 107 b have differing compositions, and are combined to form a feed107, which is then combined with hydrogen feed streams 111 and 117 b anddelivered to the hydrogenation reactor(s). Drawing two middle effluentswith different compositions at different locations have unexpectedtechnical advantages. It was found that if only one middle effluent isdrawn from a single location on column T1, certain undesirablecomponents, such as hydroxycyclohexanone(s), can accumulate in columnT1. It is believed that hydroxycyclohexanone(s) can undergo dehydrationto form cyclohexenone, which can cause fouling inside column T1. Bydrawing middle effluents at different height locations on the column,one can effectively reduce the accumulation of such undesirablecomponents and the probability of fouling inside the column.

FIG. 7 is a schematic diagram showing a portion of an exemplaryprocess/system of the present disclosure similar to those shown in FIGS.1-6, but comprising a side stripper column T4 before the primaryfractionation column T1 configured for removing at least a portion ofthe light components from the phenol/cyclohexanone/cyclohexylbenzenefeed fed to the primary fractionation column T1 to reduce or preventcatalyst poisoning in the hydrogenation reactor. It is believed thatcertain light components (i.e., components having normal boiling pointslower than cyclohexanone), if contained in thephenol/cyclohexanone/cyclohexylbenzene feed into the hydrogenationreaction zone, can poison the dehydrogenation catalyst, causingpremature reduction of the performance and life of the catalyst. Thus,in this figure, the phenol/cyclohexanone/cyclohexylbenzene feed 102 isfirst fed into a side stripper T4 smaller than column T1 to obtain anupper effluent 105 a rich in light components and depleted in phenol andcyclohexylbenzene and a lower effluent 103 depleted with the lightcomponents. The upper effluent 105 a is then combined with the firstupper effluent 105 b obtained from the primary fractionation column T1to form a stream 105, which is then delivered to the cyclohexanonepurification column T2. The lower effluent 103 is then delivered to theprimary fractionation column T1 as thephenol/cyclohexanone/cyclohexylbenzene feed. By adding a small,relatively inexpensive side stripper T4, one can remove a great majorityof the light components (e.g., C1-C6 organic acids) prone to poisoningthe hydrogenation catalyst.

FIG. 8 shows an alternative to the configuration of FIG. 7. In thisfigure, instead of placing a side stripper T4 before the primaryfractionation column T1, a side stripper T5 is placed behind column T1,which receives the first middle effluent 107 as a feed, produces anupper effluent 193 rich in light components prone to poisoning thehydrogenation catalyst (e.g., C1-C6 organic acids), which is recycled tocolumn T1 at a location higher than the location where effluent 107 isdrawn, and a lower effluent 195 depleted in such light components,which, together with hydrogen feeds 111 and 117 b, is delivered to thehydrogenation reactor as a portion or all of thephenol/cyclohexanone/cyclohexylbenzene feed 151.

FIG. 9 is a schematic diagram showing an exemplary portion of aprocess/system of the present disclosure similar to those shown in FIGS.1-8 comprising a side stripper column T6 after the cyclohexanonepurification column T2, configured to reduce amounts of light componentsfrom the final cyclohexanone product. In this figure, the first uppereffluent 105 comprising primarily cyclohexanone and light componentsobtained from the primary fractionation column T1 is delivered tocyclohexanone purification column T2, where three effluents areobtained: a second upper effluent 121 rich in light components such aswater and methylcyclopentanone and depleted in cyclohexanone andcyclohexanol, a second middle effluent 123 rich in cyclohexanone anddepleted in light components and cyclohexanol, and a second lowereffluent 125 rich in cyclohexanol. Effluent 121 is first cooled down bya heat exchanger 197, then delivered to a separation drum D2 to obtain aliquid phase 199, which is recycled to column T2, and a vapor phase 201,which is cooled again by a heat exchanger 203, and delivered to anotherseparation drum D3 to obtain a liquid phase which is partly recycled asstream 205 to drum D2, and partly delivered to storage S5, and a vaporphase 206 which can be purged. Effluent 123 is delivered to a sidestripper T6 where the following streams are produced: a substantiallypure cyclohexanone stream 211 in the vicinity of the bottom thereof,which is delivered to a storage S7; and a lights stream 209, which isrecycled to the column T2 at a location above 123.

In all of the above drawings, the phenol/cyclohexanone/cyclohexylbenzenefeed delivered to the hydrogenation reactor is wholly obtained from oneor more middle effluents from primary fractionation column T1. However,it is contemplated that, additionally, a second phenol feed streamcomprising phenol at a concentration not lower than the feed obtainedfrom column T1 can be fed to the hydrogenation reactor, eitherindependently and separately or after being combined with the feedobtained from column T1 and/or hydrogen feed. For example, the secondphenol stream may comprise substantially pure phenol having a phenolconcentration, based on its total weight, of at least Cphol(f2) wt %,where Cphol(f2) can be, e.g., 80, 82, 84, 85, 86, 88, 90, 91, 92, 93,94, 95, 96, 97, 98, 99, 99.5, 99.8, or even 99.9.

Uses of Cyclohexanone and Phenol

The cyclohexanone produced through the processes disclosed herein may beused, for example, as an industrial solvent, as an activator inoxidation reactions and in the production of adipic acid, cyclohexanoneresins, cyclohexanone oxime, caprolactam, and nylons, such as nylon-6and nylon-6,6.

The phenol produced through the processes disclosed herein may be used,for example, to produce phenolic resins, bisphenol A, ε-caprolactam,adipic acid, and/or plasticizers.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. For this reason, then, reference shouldbe made solely to the appended claims for purposes of determining thetrue scope of the present invention.

The contents of all references cited herein are incorporated byreference in their entirety.

The present invention includes one or more of the following non-limitingaspects and/or embodiments.

E1. A process for making cyclohexanone, the process comprising thefollowing steps:

(I) feeding a first mixture comprising cyclohexanone, phenol, andcyclohexylbenzene into a first distillation column:

(II) obtaining from the first distillation column:

a first upper effluent comprising cyclohexanone at a concentrationhigher than in the first mixture, phenol, and cyclohexylbenzene:

a first middle effluent comprising cyclohexanone, phenol at aconcentration higher than in the first mixture, cyclohexylbenzene, andbicyclohexane produced in step (111) below; and

a first lower effluent comprising cyclohexylbenzene at a concentrationhigher than in the first mixture;

(III) feeding at least a portion of the first middle effluent andhydrogen into a hydrogenation reaction zone where phenol reacts withhydrogen and cyclohexylbenzene reacts with hydrogen in the presence of ahydrogenation catalyst under hydrogenation reaction conditions to obtaina hydrogenation reaction product comprising cyclohexanone at aconcentration higher than in the first middle effluent, phenol at aconcentration lower than the first middle effluent, cyclohexylbenzene,and bicyclohexane; and

(IV) obtaining from the hydrogenation reaction product multiple streamsincluding a first liquid product stream and a second liquid productstream:

(V) feeding the first liquid product stream into the first distillationcolumn at a location not lower than the location where the first middleeffluent is drawn;

(VI) feeding the second liquid product stream into the firstdistillation column at a location lower than the location where thefirst middle effluent is drawn.

E2. The process of E1, wherein step (IV) further comprises obtaining athird vapor stream comprising at least 50% by volume of hydrogen, andthe process further comprises:

(VII) recycling at least a portion of the third vapor stream to thehydrogenation reaction zone.

E3. The process of E1 or E2, wherein the third vapor stream comprises atleast 80% of volume of hydrogen.

E4. The process of any of E1 to E3, wherein in step (V), the firstliquid product stream is fed into the first distillation column at alocation higher than in the location where the first middle effluent isdrawn but lower than the location where the first upper effluent isdrawn.

E5. The process of any of E1 to E4, wherein in step (VI), the secondliquid product stream is fed into the first distillation column at alocation not lower than the location where the first mixture if fed intothe first distillation column.

E6. The process of any of E1 to E5, wherein in step (VI), wherein instep (VI), the second liquid product stream is fed into the firstdistillation column at a location above the first mixture with adistance from the location where the first mixture is fed into the firstdistillation column no larger than 20% of the distance between thelocation where the first mixture is fed into the distillation column andthe location where the first middle effluent is drawn from the firstdistillation column.

E7. The process of any of E1 to E6, wherein the first liquid productstream and the second liquid product stream have the same composition.

E8. The process of any of E1 to E7, wherein the first liquid productstream has a quantity larger than the second liquid product stream.

E9. The process of any of E1 to E8, wherein the ratio of the weight ofthe first liquid stream to the weight of the second liquid stream is ina range from 1.1 to 50.

E10. The process of E9, wherein the ratio of the weight of the firstliquid stream to the weight of the second liquid stream is in a rangefrom 2.0 to 5.0.

E11. The process of any of E1 to E10, wherein the bicyclohexaneconcentration in the hydrogenation product to the bicyclohexaneconcentration in the first middle effluent is in a range from 1.0 to5.0.

E12. The process of any of E1 to E11, wherein the bicyclohexaneconcentration in the hydrogenation product to the bicyclohexaneconcentration in the first middle effluent is in a range from 1.0 to1.8.

E13. The process of any of E1 to E12, wherein at least one of thefollowing conditions is met:

(i) the first mixture comprises cyclohexanone at a concentration in arange from 10 wt % 10 to 90 wt/o %;

(ii) the first mixture comprises phenol at a concentration in a rangefrom 10 wt % to 80 wt %; and

(iii) the first mixture comprises cyclohexylbenzene at a concentrationin a range from 0.001 wt % to 75 wt %:

where the percentages are based on the total weight of the firstmixture.

E14. The process of any of E1 to E13, wherein the first upper effluentfurther comprises cyclohexanol, and the process further comprises:

(VIII) feeding at least a portion of the first upper effluent into asecond distillation column; and

(IX) obtaining the following from the second distillation column:

a second upper effluent comprising cyclohexanone at a concentrationhigher than in the first upper effluent;

a third upper effluent at a location above the second upper effluent,the third upper effluent comprising components having normal boilingpoints lower than that of cyclohexanone; and

a second lower effluent comprising cyclohexanone at a concentrationlower than the first upper effluent, and cyclohexanol at a concentrationhigher than in the first upper effluent.

E15. The process of E14, wherein the second upper effluent comprisescyclohexanone at a concentration of at least 95 wt %, based on the totalweight of the second upper effluent.

E16. The process of E14 or E15, wherein:

the second lower effluent comprises cyclohexanol at a concentration in arange from 10 wt % to 80 wt %, based on the total weight of the secondlower effluent.

E17. The process of any of E1 to E16, wherein at least one of thefollowing conditions is met:

(i) the first middle effluent comprises cyclohexanone at a concentrationin a range from 1 wt % to 50 wt %;

(ii) the first middle effluent comprises phenol at a concentration in arange from 10 wt/% to 80 wt %;

(iii) the first middle effluent comprises cyclohexylbenzene at aconcentration in a range from 0.001 wt % to 30 wt/%; and

(iv) the first middle effluent comprises bicyclohexane at aconcentration in a range from 0.001 wt % to 30 wt %.

E18. The process of any of E1 to E17, wherein a second phenol-containingstream independent from the first middle effluent is fed to thehydrogenation reaction zone, the second phenol-containing streamcomprises phenol at a concentration in a range from 50 wt % to 100 wt %,based on the total weight of the second phenol-containing stream.

E19. The process of any of E1 to E18, wherein hydrogen and phenol arefed into the hydrogenation reaction zone at a hydrogen to phenol molarratio in a range from 1.0 to 10.

E20. The process of any of E1 to E19, wherein in the hydrogenationreaction zone, (i) at least 50% of the cyclohexylbenzene is present inliquid phase; and/or (ii) at least 50% of the phenol is present inliquid phase.

E21. The process of E20, wherein in the hydrogenation reaction zone, thehydrogenation conditions comprise a temperature in a range from 140° C.to 300° C. and an absolute pressure in a range from 375 kPa to 1200 kPa.

E22. The process of any of E1 to E21, wherein in the hydrogenationreaction zone, (i) at least 90% of the cyclohexylbenzene present is invapor phase; and/or (ii) at least 90% of the phenol present is in vaporphase.

E23. The process of E22, wherein in the hydrogenation reaction zone, thehydrogenation reaction conditions comprise a temperature in a range from140° C. to 300° C. and an absolute pressure in a range from 100 kPa to400 kPa.

E24. The process of any of E1 to E23, wherein at least one of theconditions is met:

(i) the hydrogenation reaction product comprises cyclohexanone at aconcentration in a range from 20 wt % to 90 wt %;

(ii) the hydrogenation reaction product comprises phenol at aconcentration in a range from 1 wt % to 50 wt %;

(iii) the hydrogenation reaction product comprises cyclohexylbenzene ata concentration in a range from 0.001 wt % to 30 wt %; and

(iv) the hydrogenation reaction product comprises bicyclohexane at aconcentration in a range from 0.001 wt % to 30 wt %;

where the percentages are based on the total weight of the hydrogenationreaction product.

E25. The process of any of E1 to E24, wherein the hydrogenation reactionproduct further comprises cyclohexanol at a concentration in a rangefrom 0.01 wt % to 10 wt %, based on the total weight of thehydrogenation reaction product.

E26. The process of any of E1 to E25, wherein at least one of thefollowing conditions is met:

(i) the ratio of the concentration of cyclohexylbenzene in the firstmiddle effluent to the concentration of cyclohexylbenzene in thehydrogenation reaction product is in a range from 0.10 to 10:

(ii) the ratio of the concentration of bicyclohexane in thehydrogenation reaction product to the concentration of bicyclohexane inthe first middle effluent is in a range from 0.10 to 10; and

(iii) the ratio of the concentration of cyclohexanol in thehydrogenation reaction product to the concentration of cyclohexanol inthe first middle effluent is in a range from 0.10 to 10:

where the concentrations are weight percentages based on the totalweight of the hydrogenation reaction product or the total weight of thefirst middle effluent, respectively.

E27. The process of any of E1 to E26, wherein the first mixture in step(I) is obtained by a cleavage process comprising:

(I-A) contacting a cleavage feed mixture comprising1-phenyl-1-cyclohexane-hydroperoxide and cyclohexylbenzene with an acidcatalyst in a cleavage reactor to obtain a cleavage reaction product.

E28. The process of E27, wherein in step (I-A), the acid is a liquidacid, and the cleavage process further comprises:

(I-B) adding a basic material into the cleavage reaction product toobtain the first mixture.

E29. The process of E28, wherein the cleavage feed mixture is obtainedby:

(I-A-1) contacting benzene with hydrogen in the presence of ahydroalkylation catalyst under hydroalkylation conditions to produce ahydroalkylation product mixture comprising cyclohexylbenzene;

(I-A-2) contacting the cyclohexylbenzene with oxygen in the presence ofa catalyst to produce an oxidation reaction product mixture comprising1-phenyl-1-cyclohexane-hydroperoxide; and

(I-A-3) providing the cleavage feed mixture from the oxidation reactionproduct mixture.

E30. The process of any of E1 to E29, further comprising:

(X) feeding at least a portion of the first lower effluent to a thirddistillation column; and

(XI) obtaining the following from the third distillation column:

a third upper effluent comprising cyclohexylbenzene; and

a third lower effluent comprising components having boiling pointshigher than cyclohexylbenzene.

E31. The process of E30, wherein the third upper effluent comprisescyclohexylbenzene at a concentration of at least 90 wt %, based on thetotal weight of the third upper effluent.

E33. The process of E30 or E31, wherein at least a portion of the thirdupper effluent is recycled to step (I-A-2).

1. A process for making cyclohexanone, the process comprising thefollowing steps: (I) feeding a first mixture comprising cyclohexanone,phenol, and cyclohexylbenzene into a first distillation column; (II)obtaining from the first distillation column: a first upper effluentcomprising cyclohexanone at a concentration higher than in the firstmixture, phenol, and cyclohexylbenzene; a first middle effluentcomprising cyclohexanone, phenol at a concentration higher than in thefirst mixture, cyclohexylbenzene, and bicyclohexane at least partlyproduced in step (III) below; and a first lower effluent comprisingcyclohexylbenzene at a concentration higher than in the first mixture;(III) feeding at least a portion of the first middle effluent andhydrogen into a hydrogenation reaction zone where phenol reacts withhydrogen and cyclohexylbenzene reacts with hydrogen in the presence of ahydrogenation catalyst under hydrogenation reaction conditions to obtaina hydrogenation reaction product comprising cyclohexanone at aconcentration higher than in the first middle effluent, phenol at aconcentration lower than the first middle effluent, cyclohexylbenzene,and bicyclohexane; (IV) obtaining from the hydrogenation reactionproduct multiple streams including a first liquid product stream and asecond liquid product stream; (V) feeding the first liquid productstream into the first distillation column at a location not lower thanthe location where the first middle effluent is drawn; and (VI) feedingthe second liquid product stream into the first distillation column at alocation lower than the location where the first middle effluent isdrawn.
 2. The process of claim 1, wherein step (IV) further comprisesobtaining a third vapor stream comprising at least 50% by volume ofhydrogen, and the process further comprises: (VII) recycling at least aportion of the third vapor stream to the hydrogenation reaction zone. 3.The process of claim 1, wherein in step (V), the first liquid productstream is fed into the first distillation column at a location higherthan the location where the first middle effluent is drawn but lowerthan the location where the first upper effluent is drawn.
 4. Theprocess of claim 1, wherein in step (VI), the second liquid productstream is fed into the first distillation column at a location not lowerthan the location where the first mixture is fed into the firstdistillation column.
 5. The process of claim 1, wherein in step (VI),the second liquid product stream is fed into the first distillationcolumn at a location above the first mixture with a distance from thelocation where the first mixture is fed into the first distillationcolumn no larger than 20% of the distance between the location where thefirst mixture is fed into the distillation column and the location wherethe first middle effluent is drawn from the first distillation column.6. The process of claim 1, wherein the first liquid product stream andthe second liquid product stream have the same composition.
 7. Theprocess of claim 1, wherein the first liquid product stream has aquantity larger than the second liquid product stream.
 8. The process ofclaim 1, wherein the ratio of the weight of the first liquid stream tothe weight of the second liquid stream is in a range from 1.1 to
 50. 9.The process of claim 8, wherein the ratio of the weight of the firstliquid stream to the weight of the second liquid stream is in a rangefrom 2.0 to 5.0.
 10. The process of claim 1, wherein the ratio of thebicyclohexane concentration in the hydrogenation product to thebicyclohexane concentration in the first middle effluent is in a rangefrom 1.0 to 5.0.
 11. The process of claim 10, wherein the ratio of thebicyclohexane concentration in the hydrogenation product to thebicyclohexane concentration in the first middle effluent is in a rangefrom 1.0 to 1.8.
 12. The process of claim 1, wherein at least one of thefollowing conditions is met: (i) the first mixture comprisescyclohexanone at a concentration in a range from 10 wt % to 90 wt %;(ii) the first mixture comprises phenol at a concentration in a rangefrom 10 wt % to 80 wt %; and (iii) the first mixture comprisescyclohexylbenzene at a concentration in a range from 0.001 wt % to 75 wt%; where the percentages are based on the total weight of the firstmixture.
 13. The process of claim 1, wherein the first upper effluentfurther comprises cyclohexanol, and the process further comprises:(VIII) feeding at least a portion of the first upper effluent into asecond distillation column; and (IX) obtaining the following from thesecond distillation column: a second upper effluent comprisingcyclohexanone at a concentration higher than in the first uppereffluent; a third upper effluent at a location above the second uppereffluent, the third upper effluent comprising components having normalboiling points lower than that of cyclohexanone; and a second lowereffluent comprising cyclohexanone at a concentration lower than thefirst upper effluent, and cyclohexanol at a concentration higher than inthe first upper effluent.
 14. The process of claim 1, wherein at leastone of the following conditions is met: (i) the first middle effluentcomprises cyclohexanone at a concentration in a range from 1 wt % to 50wt %; (ii) the first middle effluent comprises phenol at a concentrationin a range from 10 wt % to 80 wt %; (iii) the first middle effluentcomprises cyclohexylbenzene at a concentration in a range from 0.001 wt% to 30 wt %; and (iv) the first middle effluent comprises bicyclohexaneat a concentration in a range from 0.001 wt % to 30 wt %.
 15. Theprocess of claim 1, wherein a second phenol-containing streamindependent from the first middle effluent is fed to the hydrogenationreaction zone, the second phenol-containing stream comprising phenol ata concentration in a range from 50 wt % to 100 wt %, based on the totalweight of the second phenol-containing stream.
 16. The process of claim1, wherein hydrogen and phenol are fed into the hydrogenation reactionzone at a hydrogen to phenol molar ratio in a range from 1.0 to
 10. 17.The process of claim 1, wherein at least one of the following conditionsis met: (i) the hydrogenation reaction product comprises cyclohexanoneat a concentration in a range from 20 wt % to 90 wt %; (ii) thehydrogenation reaction product comprises phenol at a concentration in arange from 1 wt % to 50 wt %; (iii) the hydrogenation reaction productcomprises cyclohexylbenzene at a concentration in a range from 0.001 wt% to 30 wt %; and (iv) the hydrogenation reaction product comprisesbicyclohexane at a concentration in a range from 0.001 wt % to 30 wt %;where the percentages are based on the total weight of the hydrogenationreaction product.
 18. The process of claim 1, wherein the hydrogenationreaction product further comprises cyclohexanol at a concentration in arange from 0.01 wt % to 10 wt %, based on the total weight of thehydrogenation reaction product.
 19. The process of claim 1, wherein atleast one of the following conditions is met: (i) the ratio of theconcentration of cyclohexylbenzene in the first middle effluent to theconcentration of cyclohexylbenzene in the hydrogenation reaction productis in a range from 0.10 to 10; (ii) the ratio of the concentration ofbicyclohexane in the hydrogenation reaction product to the concentrationof bicyclohexane in the first middle effluent is in a range from 0.10 to10; and (iii) the ratio of the concentration of cyclohexanol in thehydrogenation reaction product to the concentration of cyclohexanol inthe first middle effluent is in a range from 0.10 to 10; where theconcentrations are weight percentages based on the total weight of thehydrogenation reaction product or the total weight of the first middleeffluent, respectively.
 20. The process of claim 1, wherein the firstmixture in step (I) is obtained by a cleavage process comprising: (I-A)contacting a cleavage feed mixture comprising1-phenyl-1-cyclohexane-hydroperoxide and cyclohexylbenzene with an acidcatalyst in a cleavage reactor to obtain a cleavage reaction product.21. The process of claim 20, wherein in step (I-A), the acid is a liquidacid, and the cleavage process further comprises: (I-B) adding a basicmaterial into the cleavage reaction product to obtain the first mixture.22. The process of claim 21, wherein the cleavage feed mixture isobtained by: (I-A-1) contacting benzene with hydrogen in the presence ofa hydroalkylation catalyst under hydroalkylation conditions to produce ahydroalkylation product mixture comprising cyclohexylbenzene; (I-A-2)contacting the cyclohexylbenzene with oxygen in the presence of acatalyst to produce an oxidation reaction product mixture comprising1-phenyl-1-cyclohexane-hydroperoxide; and (I-A-3) providing the cleavagefeed mixture from the oxidation reaction product mixture.
 23. Theprocess of claim 22, further comprising: (X) feeding at least a portionof the first lower effluent to a third distillation column; and (XI)obtaining the following from the third distillation column: a thirdupper effluent comprising cyclohexylbenzene; and a third lower effluentcomprising components having boiling points higher thancyclohexylbenzene.
 24. The process of claim 23, wherein the third uppereffluent comprises cyclohexylbenzene at a concentration of at least 90wt %, based on the total weight of the third upper effluent.
 25. Theprocess of claim 23, wherein at least a portion of the third uppereffluent is recycled to step (I-A-2).